Biochem Ok FinalBiochem ok final

Chapter 14 Bioenergetics and Oxidative MetabolismMultiple Choice 1. Which of the following enzymes in the tricarboxylic acid cycle requires the same set of cofactors or coenzymes as the pyruvate dehydrogenase complex? A. alpha-ketoglutarate dehydrogenase B. isocitrate dehydrogenase C. succinate dehydrogenase D. malate dehydrogenase E. citrate synthase Ans: A 2. Which enzyme catalyzes substrate level phosphorylation? A. succinyl-CoA synthase B. citrate synthase C. alpha-ketoglutarate dehydrogenase D. aconitase E. succinate dehydrogenase Ans: A 3. The tricarboxylic acid cycle does not occur in which cells in your body? A. skeletal muscle cells B. liver parenchymal cells C. adipose cells D. renal tubular epithelium E. erythrocytes Ans: E 4. All of the following are intermediates of the Krebs cycle EXCEPT A. cis-aconitate. B. pyruvate. C. fumarate. D. succinyl-CoA. E. malate. Ans: B 5. Which of the following contains high energy bonds? A. B. C. D. E. glucose 6-phosphate. creatine phosphate. acetoacetate. citric acid. glutamine Ans: B 6. The iron in the cytochromes function in biological systems by A. undergoing oxygenation and deoxygenation. B. undergoing oxidation and reduction. C. combining with phosphate. D. undergoing dehydration and hydration. E. interchanging with the iron of adrenodoxin. Ans: B 7. The structure of oxidized flavin differs from that of fully reduced flavin by A. one proton. B. one electron and one proton. C. two electrons. D. two protons. E. two electrons and two protons. Ans: E 8. M1755lAll of the following concerning the human mitochondrial genetic apparatus are true EXCEPT A. the mitochondrial genome is a circular DNA. B. the mitochondrial genome codes for several essential proteins for oxidative phosphorylation. C. the mitochondrial genome exhibits maternal inheritance. D. the mitochondrial genome uses the same genetic code as the nuclear genome. E. a mitochondrial DNA mutation results in Leber's Hereditary Optic Neuropathy. Ans: D 9. In order to be considered a high energy compound, a metabolic intermediate must have a free energy of hydrolysis, (delta G0 hydrolysis), equal to, or greater than ______ kilocalories / mole. A. + 5.3 B. - 5.3 C. + 7.3 D. - 7.3 E. + 9.3 Ans: D 10. All of the following reactions are observed in the tricarboxylic acid cycle EXCEPT A. hydration of cis-aconitate to isocitrate B. dehydration of citric acid to form cis-aconitic acid C. oxidative decarboxylation of alpha-ketoglutaric acid to form succinyl-CoA D. hydration of fumaric acid to form malic acid E. decarboxylation of citric acid to form oxalosuccinic acid Ans: E 11. The mammalian pyruvate dehydrogenase complex A. catalyzes the conversion of pyruvate to acetyl-CoA and carbon dioxide. B. catalyzes the conversion of pyruvate to oxaloacetate. C. functions as a tetramer made up of two types of subunits which are identical to those of either muscle (M) or heart (H) origin. D. utilizes NAD as the only required coenzyme. E. catalyzes the oxidation of lactate to pyruvate. Ans: A 12. The effect of malonate on succinate dehydrogenase is A. noncompetitive inhibition. B. competitive inhibition. C. irreversible inhibition. D. uncompetitive inhibition. E. no inhibition; it is the product of the reaction. Ans: B 13. The prosthetic group in mitochondrial cytochromes is A. FeS B. NAD C. heme D. flavin E. ADP Ans: C 14. The free energy change for a reaction at equilibrium is A. less than 1. B. zero. C. greater than 1. D. equal to -RT 1n Keq. E. can be utilized to do work in the cell. Ans: B 15. The enzymes of the respiratory chain are A. in the cytosol. B. on the outer membrane of the mitochondria. C. on the inner membrane of the mitochondria. D. in the mitochondrial matrix. E. in the lysosomes. Ans: C 16. How is uncoupling produced in brown adipose tissue? A. Action of thyroid hormone on a mitochondrial thyroid receptor B. Activation of UCP-1 by fatty acids C. Induction of ATPase D. Synthesis of a small non-protein uncoupling molecule E. Transfer of protons out of the mitochondrial matrix Ans: B 17. Oligomycin inhibits oxidative phosphorylation by: A. Binding to cytochromes B. Channeling protons C. Binding to coenzyme Q D. Oxidizing FAD E. Inhibiting phosphorylation Ans: E 18. Which coenzyme is NOT required for the activity of the pyruvate dehydrogenase complex? A. biotin B. lipoic acid C. thiamine pyrophosphate D. coenzyme A E. flavin adenine dinucleotide Ans: A 19. Anaplerotic reactions A. are generally endergonic. B. are typified by that catalyzed by pyruvate kinase. C. are defined as reactions which produce pyruvate. D. increase the concentrations of intermediates of the Krebs cycle. E. are typified by those catalyzed by pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase. Ans: A 22. D. B. a protonated form of coenzyme Q. B. acetyl-CoA. Ans: B 23. The chemiosmotic hypothesis suggests that the potential energy of the electrons moving down the mitochondrial electron transport chain from a negative to a positive oxidation potential is initially conserved in the form of a A. how many proteins are taken up from the matrix side of the inner membrane and how many are released into the inner membrane space respectively? A. with a high chemical bond energy. NADH. The definition of a high energy bond is a bond A. with a large negative free energy change on hydrolysis.Ans: D 20. E. ATP synthesis is driven by a pH gradient and a membrane potential. B. proton gradient across the membrane. glucose 6-phosphate. the respiratory chain consists of three enzyme complexes linked by two mobile electron carriers. E. E.4-dinitrophenol. which is highly unstable. C. D. D. All of the following statements about oxidative phosphorylation are correct EXCEPT A. 1 and 2 . ADP. D. In the “Q cycle” for electron transfer and protein pumping in Complex III of the mitochondrial electron transport chain. B. a different conformational form of the electron carriers. Ans: B 21. a high energy phosphate bond. C. with a high phosphate group transfer potential. which is highly exergonic. a reduced non-heme iron protein. C. Ans: E 24. An allosteric activator of mitochondrial NAD-linked isocitrate dehydrogenase is A. ATP synthase translocates ATP through mitochondrial membrane. alpha-ketoglutarate. the process can be uncoupled by 2. C. All of the following molecules. Glucose C. B. without further metabolism. Ans: E 27. A simple explanation of the action of an uncoupler of mitochondrial oxidative phosphorylation is that it is any agent that A. D. oxygen. Ans: C . inorganic phosphate. blocks the oxidation of reduced cytochrome c by cytochrome oxidase. citrate synthase. E. ATP. B. E. D. succinate thiokinase. D. ADP D. Ans: B 28. pyruvate. E. O2 B. aconitase. B. D.B. C. Respiratory control refers to the striking dependence of respiration on the availability of A. can cross the inner membrane of functioning mitochondria EXCEPT A. The enzyme which catalyzes the entrance of acetyl CoA into the Krebs cycle is A. C. pyruvate dehydrogenase. acetyl CoA. C. C. electrons Ans: C 26. prevents formation of ATP by interacting with and blocking proton transport through the proton translocating ATPase. isocitric dehydrogenase. acts to conduct protons back into the mitochondrial matrix without accompanying formation of ATP. blocks proton conductance and slows oxygen uptake rates. 2 and 2 2 and 4 4 and 2 4 and 4 Ans: C 25. ATP E. 32.29. Malate production from succinyl CoA D. acts to conduct protons back into the mitochondrial matrix without accompanying formation of ATP. B. E. What thermodynamic parameters are compatible with the spontaneity of a chemical reaction? A. positive standard free energy change and high activation energy. A one-step rotation of 180o C. prevents formation of ATP by interacting with and blocking proton transport through the proton translocating ATPase. Conformation change of the b subunit resulting in release of protons E. blocks the transfer of electrons from complex I to complex II. What effect does the chemical uncoupler 2. D. blocks the transfer of electrons from NADH to O2 D. Ans: C 30. positive standard free energy change only. positive standard free energy change and low activation energy. stimulates ATP synthesis E. blocks the oxidation of reduced cytochrome c by cytochrome oxidase. Employs a flavoprotein: A. Ans: B 31. Rotation of the g subunit in 120o steps Ans: E 33. allows electron transport to proceed without ATP synthesis C. B. D. C.4-dinitrophenol have on mitochondria? A. negative standard free energy change and high activation energy. How does the “binding-change model” for synthesis and hydrolysis of ATP in the inner mitochondrial membrane work?? A. negative standard free energy change. inhibits electron transport and oxidative phosphorylation B. pyruvate production from fructose E. A simple explanation of the action of an uncoupler of mitochondrial oxidative phosphorylation is that it is any agent that A. “Flipping” of orientation of F1Fo-ATP synthase in the membrane B. Lactate production from glucose C. C. Change in the binding constant for ATP on the T subunit D. Succinate production from succinyl CoA . Glucose production from glycogen B. blocks proton conductance and slows oxygen uptake rates. Ans: E 37. Which of the following is the only mobile electron carrier in the electron transport system that is neither permanently associated nor covalently attached to a protein? A. FMN B. Ans: E 36. C. creatine kinase. Certain bacterial mutant lacks the kinase catalyzing the reaction ATP + GDP <==> ADP + GTP but otherwise possesses enzymes similar to those in mammals. matrix. D. isocitrate dehydrogenase E. outer membrane. pyruvate carboxylase. after conversion to glycerol phosphate. oxaloacetate dehydrogenase B. The electron transport chain of mitochondria is specifically located in the A. tonoplast. This mutant could still produce GTP from GDP by utilizing the enzyme A. B. after reaction with carnitine. coenzyme Q C. C. E. phosphoglycerate kinase. E. after oxidation to pyruvate. inner membrane.Ans: C 34. fumarase D. succinate dehydrogenase C. pyruvate kinase. succinate thiokinase. D. heme a3 . Oxaloacetate moves through the mitochondrial membrane A. E. Which of the following enzyme systems is most analogous to the pyruvate dehydrogenase complex? A. Ans: C 38. by passive diffusion. D. C. after reduction to malate. B. alpha-ketoglutarate dehydrogenase Ans: E 35. B. intermembrane space. beta-carotene. Which of the following is a potential oxidant? A. . A number of intermediates in lipid metabolism are esters of coenzyme A. C. Dental caries D. ATP E. Fe2+ Ans: A 40. Consumes ATP B. Substrate level phosphorylation in mitochondria A. Cataracts C. E. NADH D. The activity of pyruvate dehydrogenase (PDH) decreases A. as the concentration of acetyl CoA decreases. B. nicotinic acid. Is catalyzed by a flavoprotein D. pantothenic acid. Osteoporosis Ans: A 41. Produces fumarate Ans: D 42. FAD B. B. The vitamin precursor of coenzyme A is A. FeS cluster E. Produces coenzyme A E. Age spots B. NADPH C. Hair loss E. when the dephospho-enzyme is converted to its phospho form.D. FAD Ans: B 39. as the concentration of NAD increases. Ans: D 43. biotin. riboflavin. D. C. Consumes NADH C. What is the most visible sign of reactive oxygen species damage? A. FMNH2 is the electron acceptor. Which is a flavoprotein? A. NADH is the electron donor. Ans: B 46. Ans: C 44. aconitase. cytochrome c . produces heat. E. D. Ans: E 48. E. B. C. D. citrate synthase E. E. produces water. Which molecule is involved in the major step for the production of superoxide in the mitochondrial electron transport chain? A. C. The uncoupling of oxidative phosphorylation in the human might be of physiological importance because it A. isocitrate dehydrogenase B. carbonic anhydrase D. citrate synthase. Which of the statements below is correct for the reaction NADH + FMN + H+ ---> NAD+ + FMNH2 A. B. succinate dehydrogenase. E. malate dehydrogenase. NAD+ is the oxidant. increases carbon dioxide level in the blood. B. allows storage of nutrients. Ans: D 47. C. raises the oxygen level in the blood.D. the reaction involves only the transfer of a hydrogen atom. A major control point of the Krebs cycle is exerted at the level of A. D. as the concentration of pyruvate increases. succinate dehydrogenase C. aconitase Ans: B 45. as the concentration of AMP increases. succinyl CoA synthase. FMN is the reducing agent. E. NADH is an allosteric activator of pyruvate oxidation. Lipoamide functions in the decarboxylation of pyruvate. Succinate Ans: E 50. C. aconitase Ans: A . Alpha-ketoglutarate B. Mitochondrial protein synthesis is inhibited by chloramphenicol. Protein synthesis in mitochondria is closely integrated with cytoplasmic protein synthesis. Which statement about the pyruvate dehydrogenase complex is true? A. Each of the following statements concerning mitochondrial protein synthesis are true EXCEPT which one? A. phosphorylation catalyzed by a kinase results in decreased activity. alpha-ketoglutarate dehydrogenase D. pyruvate E. B.and NADP-linked forms? A.B. Ans: C 52. Which enzyme occurs in mammals in both NAD. isocitrate dehydrogenase B. C. E. Mitochondrial protein synthesis is initiated by N-formylmet-tRNA fmet. Ans: B 51. A substrate with a P:O ratio of 1. Malate D. D. The mitochondrial genome codes for only certain proteins of the inner mitochondrial membrane. The function of FAD is to oxidize NADH. Coenzyme A is covalently bound to a lysine residue in one of the proteins of the complex. E. The enzymes of the respiratory chain are all coded by mitochondrial genes. C. D. D. cytochrome oxidase NADH dehydrogenase Succinate dehydrogenase Ubiquinone Ans: E 49. Isocitrate C.5 is: A. B. succinate dehydrogenase C. citrate synthase E. What else can cause hydrogen peroxide to form this toxic species? A. How many molecules of NAD are reduced as one molecule of pyruvate is metabolized through one turn of the Krebs cycle? A. Fe2+ B. electron transport cannot be used to regenerate NAD+ D. cytochrome oxidase. 2 C. E. 1 B. Na+ Ans: A 57. . pyruvate dehydrogenase. Cyanide is toxic because it inhibits A. 5 Ans: D 54. requires a proton gradient. B. C. substrate-level phosphorylation may be differentiated from mitochondrial oxidative phosphorylation in that all substrate-level phosphorylation A. phosphorylase. D. requires inorganic phosphate. D. epinephrine levels are increased E. is characterized by all of the above. K+ C. can continue in the presence of dinitrophenol. B. In liver cells. E.53. NADH-dehydrogenase. glycogenolysis is decreased. 4 E. C. C. How does lack of oxygen in the cell decrease TCA cycle activity? A. Ans: A 56. synthesis of lactic acid from pyruvate is inhibited B. A reaction between hydrogen peroxide and superoxide can produce hydroxyl radicals. Mg2+ D. Ans: E 55. Mn2+ E. succinate dehydrogenase. 3 D. increased malonyl CoA inhibits carnitine acyl transferase I. causing less requirement for the TCA cycle. forms GTP as the immediate product. E. oxidation. oxidative phosphorylation. The formation of GTP in the citric acid cycle is an example of A. a proton translocating system oriented asymmetrically across the membrane. D. substrate level phosphorylation. B. microsomes. a direct coupling of electron transport to phosphorylation. Ans: B 62. mitochondria. reduction. alpha-ketoglutarate ----> succinyl CoA E. citrate synthase E. B. Ans: E 59. All of the following items are requirements of the chemiosmotic mechanism of oxidative phosphorylation EXCEPT A. aconitase Ans: D 61. C. fumarase D. C. C. The ratio of NADH/NAD is greatest in A. Which reaction in the citric acid cycle requires the participation of lipoic acid and thiamine pyrophosphate? A. D.Ans: C 58. cytosol. Oxaloacetate is a substrate of which enzyme? A. citrate ----> isocitrate C. proton impermeable membrane. a topologically closed. nucleus. isocitrate ----> alpha-ketoglutarate D. an ATPase which can be driven in reverse by a proton gradient across the membrane. D. succinyl CoA ----> succinate Ans: D 60. isocitrate dehydrogenase B. . B. phosphorolysis. acetyl CoA + oxaloacetate ----> citrate B. succinate dehydrogenase C. H2O2 C. NADPH Ans: C 66. O2. catalase. O2 D. Ans: E 65. 1. ADP D.3-bisphosphoglycerate E. oxaloacetate D. ATP E. pyruvate . An enzyme which catalyzes the conversion of hydrogen peroxide to water and oxygen is A. the rate of oxidative phosphorylation is governed by the concentration of A. Ans: A 64.E. H2O B. ADP D. acetyl CoA E. Acetyl-CoA B. peroxide mutase. citrate B. D. a cytochrome. C. ATP B. Which of the following would NOT be considered a high energy compound? A. B. glutathione peroxidase. Pi C. Which is the immediate product of an anaplerotic reaction related to the Krebs cycle? A. What is the most reactive form of oxygen? A. malate C. In tightly coupled mitochondria.Ans: D 63. phosphoenolpyruvate C. OH. E. glyceraldehyde 3-phosphate Ans: E 67. invertase. A typical enzyme-catalyzed reduction reaction occurring in a biosynthetic pathway would require the cofactor A. C. intermembrane space. site I of the respiratory chain. Ans: A 69. It is reduced by the reduced form of the cytochrome bc1 complex. outer mitochondrial membrane. E. it is water soluble. B. E. All enzymes of the Krebs cycle. B. alpha-ketoglutarate D. Which is a tricarboxylic acid? A. ATP synthase. except for succinate dehydrogenase.Ans: C 68. Unlike the other mitochondrial cytochromes. inner mitochondrial membrane. site III of the respiratory chain. E. succinate C. FADH2 C. C. acetate Ans: D 70. It is visibly colored. citrate E. mitochondrial matrix. NAD+ B. D. D. D. site II of the respiratory chain. C. FAD . All of the following statements about cytochrome c are correct EXCEPT which one? A. B. the adenine nucleotide exchange protein. The reduced form of the protein participates in electron transport by directly donating electrons to oxygen. Oligomycin has a direct inhibitory effect on A. Ans: A 72. are found in the A. cytosol. It contains iron which undergoes reversible oxidation and reduction during electron transport. oxaloacetate B. Ans: B 71. Depletion of acetyl-CoA Ans: B 74. 3 B. 6 E. How many moles of ATP can be formed from ADP during the complete oxidation of one mole of pyruvate to carbon dioxide and water in normal liver cells? A. lactate C. 3 B. Which of the following would NOT have an inhibitory effect on the flow of metabolites through the citric acid cycle? A. 7 . oxaloacetate E. glutamate B. 12 D. 9 C. NADP+ Ans: D 73. 36 Ans: D 76. 5 D. Electrons from NADH produced in the cytosol by glycolysis may be transported into the mitochondrion and to the electron transport chain through which of the following compounds? A. 15 E. Limited availability of oxaloacetate D. NADPH E. malate D. Oxidation of one molecule of pyruvate by the combined action of the pyruvate dehydrogenase complex and the enzymes of the citric acid cycle is thought to result in the generation of how many pairs of electrons which can move through the electron transport chain? A.D. High levels of ATP relative to ADP B. Depletion of NADH by its conversion to NAD+ C. 4 C. High levels of citrate E. pyruvate Ans: C 75. B. D. D. is inhibited directly by rotenone and amytal. phosphoenol. phosphoanhydride. B. C.Ans: C 77. Ans: A 79. A proton C. the linkage between each of the phosphate groups is a A. Golgi apparatus D. B. The steady-state activity of pyruvate dehydrogenase (PDH) is reduced by increases in all of the following EXCEPT A. cytosol Ans: D 78. Cytochrome a. contains copper which is required for the reduction of oxygen. phosphomonoester. D. Succinate dehydrogenase is found in which subcellular fraction of the liver? A. A radical is a molecule with a highly reactive unpaired electron in the outer shell. cyclic AMP. What does it need to attain its preferred state? A. can be reduced directly by cytochrome b. C. C. ingestion of ethanol. phosphoamide. acetyl CoA. microsomes B. NADH. inner membrane of the mitochondrion E. E. is not inhibited by carbon monoxide. Another electron D. a3 (cytochrome oxidase) A. Loss of a protein E. mitochondrial matrix C. Ans: D 80. In ATP. is a terminal electron acceptor which forms hydrogen peroxide upon reduction of oxygen. E. A pair of electrons B. Loss of the single electron Ans: C 81. phosphodiester. . acetyl-CoA. glycerol-3-phosphate D. ATP. The initial step in the reactions catalyzed by the pyruvate dehydrogenase complex is the formation of carbon dioxide and A. The enzyme in the citric acid cycle that catalyzes the conversion of GDP + Pi --> GTP is A. B. Ans: E 86. citrate. NADH can reduce coenzyme Q through the mediation of an enzyme associated with which of the following? . or associated with the mitochondrial electron transport chain EXCEPT A. proteins containing non_heme iron and sulfur. B. B. electrons Ans: E 85. malate dehydrogenase. E. C. NAD+ B. substrate level phosphorylation. a two carbon unit covalently linked to thiamine pyrophosphate. Ans: E 83. isocitrate dehydrogenase. coenzyme Q (ubiquinone). cytochromes. D. All of the following are found in. proteins containing FMN. E. Ans: D 84. the reduction of NAD+. fumarase. The glycerol phosphate shuttle results in the transport of which of the following from the cytosol into the mitochondrial matrix? A. succinate dehydrogenase. C. Ans: C 82. D. E.E. dihydroxyacetone phosphate E. NADH C. D. succinyl-CoA synthetase. C. lipoic acid in its reduced form. A. B. C. D. E. cytochrome c Lipoic acid Iron-Porphyrin cytochrome a FMN Ans: E 87. Uncouplers of oxidative phosphorylation A. increase ATP synthesis. B. decrease oxygen consumption. C. decrease substrate oxidation. D. short circuit a proton gradient. E. include substances such as penicillin. Ans: D 88. All of the following are components of the mitochondrial electron transport chain EXCEPT A. cytochrome c. B. thiamine pyrophosphate. C. coenzyme Q. D. cytochrome b. E. flavoprotein. Ans: B 89. There cannot be significant net formation of glucose from stearic acid in a mammal because of the irreversibility of the reaction catalyzed by A. pyruvate kinase. B. pyruvate carboxylase C. hexokinase. D. pyruvate dehydrogenase. E. glucose 6-phosphate dehydrogenase. Ans: D 90. The synthesis of ATP in oxidative phosphorylation occurs at which of the following locations in the cell? A. cytosol B. plasma membrane C. outer membrane of the mitochondrion D. inner membrane of the mitochondrion E. nuclear membrane Ans: D 91. All of these vitamins are essential for the activity of mammalian pyruvate dehydrogenase EXCEPT A. thiamine. B. pyridoxine. C. niacin. D. pantothenic acid. E. riboflavin. Ans: B 92. M17192Lipoamide is a carrier of activated A. acyl groups. B. aldehydes C. carboxylates D. methyl groups E. phosphoryl groups Ans: A 93. All of the following metabolites are oxidized by an NAD-linked enzyme in liver cells EXCEPT A. isocitrate. B. malate. C. lactate. D. succinate. E. glyceraldehyde 3-phosphate. Ans: D 94. The locus for rotenone inhibition of mitochondrial metabolism is A. malate dehydrogenase. B. NADH dehydrogenase. C. cytochrome oxidase. D. ATPase. E. succinate dehydrogenase. Ans: B 95. All of the following statements are consistent with the chemiosmotic hypothesis of oxidative phosphorylation EXCEPT which one? A. Agents which uncouple oxidative phosphorylation from electron transport disrupt permeability barriers such that mitochondrial membranes become permeable to protons. B. The term electrochemical gradient or proton gradient operationally describes the free energy generated by electron transport which drives phosphorylation of ADP. C. Protons are transferred into the mitochondria during electron transport establishing a pH gradient. D. Intact mitochondrial membranes are necessary for oxidative phosphorylation to occur. E. electron carriers of the electron transport chain are vectorially oriented. Ans: C 96. All of the following enzymes require a niacin-derived coenzyme EXCEPT which one? A. pyruvate dehydrogenase B. Glyceraldehyde 3-phosphate dehydrogenase C. Malate dehydrogenase D. Glucose 6-phosphate dehydrogenase E. Mitochondrial glycerol phosphate dehydrogenase Ans: E 97. Has the LEAST involvement in the oxidative burst: A. Glucose-6-phosphate dehydrogenase B. Glutathione peroxidase C. Myeloperoxidase D. NADPH oxidase E. Superoxide dismutase Ans: B 98. Thermogenesis in brown adipose tissue could not occur without increased A. calcium levels in the cytoplasm. B. secretion of ketone bodies into blood. C. uncoupling protein in the mitochondria. D. oxidation of glucose. E. synthesis of triacylglycerols. Ans: C 99. Syntheses and release of ATP in the mitochondrion from the F1_ATPase is driven by A. the discharge of a proton gradient between the intermembrane space and the matrix of the mitochondrion. B. the discharge of a proton gradient between the cytosol and the intermembrane space. C. the direct formation of a high energy compound in electron transport. D. the reduction of oxygen at the end of the electron transport chain. E. the discharge of a sodium gradient between the intermembrane space and the mitochondrial matrix. Ans: A 100. Which reaction of the Krebs cycle is not physiologically reversible? A. the formation of citrate from oxaloacetate B. the oxidation of succinate C. the oxidation of malate D. the reduction of fumarate E. the reduction of oxaloacetate Ans: A 101. A flavoprotein is required for the A. formation of glucose from glycogen. B. production of lactate from glucose. C. production of malate from succinyl CoA. D. production of pyruvate from fructose. E. production of succinate from succinyl CoA. Ans: C 102. All of the following must be catabolized to acetyl CoA before entering the Krebs cycle EXCEPT A. palmitate. B. glucose. C. lactate. D. alanine. E. glutamate. Ans: E 103. All of the following compounds would inhibit the oxidation of pyruvate by intact liver mitochondria EXCEPT A. sodium cyanide. B. rotenone. C. antimycin A. D. 2,4-dinitrophenol. E. oligomycin. Ans: D 104. Myokinase catalyzes the reaction: ADP + ADP <---> ATP + AMP. From your knowledge of high energy bonds, predict the equilibrium constant for this reaction. A. <<1. B. >>1. C. approximately 1. D. 0. E. none of the above. Ans: C 109. The citric acid cycle is slowed by which of the following? A. Which does NOT occur among the reactions catalyzed by the pyruvate dehydrogenase complex of liver mitochondria? A. the reduction of a disulfide. anaerobic glycolysis for regeneration of NAD. An intermediate in the Krebs cycle which is an immediate precursor of CO2 is A. E. NAD+ and ADP D. ADP and AMP B. the beta-oxidation of fatty acids. C. citrate B. C. citrate. oxaloacetate and ADP C. oxaloacetate E. The main function of the glycerol phosphate shuttle is in A. formation of a covalent bond between a two-carbon unit and thiamine pyrophosphate. malate Ans: A 107. the transport of reducing equivalents into mitochondria from NADH formed during glycolysis. alpha-ketoglutarate D. the transfer of an acetyl group to coenzyme A. formation of an acetyl derivative of lipoic acid. the biosynthesis of triacylglycerols. NAD+ and oxaloacetate Ans: D 108. . B.Ans: C 105. Which Krebs cycle intermediate helps to regulate the overall rate of glycolysis by direct influence on the activity of phosphofructokinase? A. the biosynthesis of serine for use in mitochondrial protein synthesis. malate. Ans: D 106. a redox reaction involving coenzyme Q. NADH and ATP E. D. B. D. B. C. succinate C. isocitrate. E. The complex contains three different enzyme activities. C. Which of the following enzymes is important in protecting the cell from the potential toxicity of superoxide anion and its derivatives? A. E. B.dephosphorylation. superoxide dismutase B. D. The oxidation of NADH involves the removal of A. Which statement about the mammalian pyruvate dehydrogenase complex is FALSE? A. cytochrome c/reduced cytochrome c C. The complex functions in the matrix of mitochondria. two electrons. in the matrix. succinate. Oxidative phosphorylation in the mitochondrion is carried out by enzymes A. O2/H2O Ans: E 113. one proton and one electron. one electron. NADP/NADPH B. in the outer membrane. E. Lipoic acid is covalently bound to one of the proteins of the complex. The complex is not regulated by phosphorylation. D. C. Ans: D 114. All of the above. in the intermembrane space. E. Ans: B 112. FAD/FADH2 D. in the inner membrane. NAD/NADH E. aconitate.D. B. Which has the most POSITIVE reduction potential? A. C. Ans: D 111. D. The complex contains five different coenzymes. B. one hydrogen atom. E. Ans: C 110. a hydride ion. cytochrome oxidase . D. C. is condensed with unlabeled oxaloacetate and the product is oxidized via the Krebs cycle. C. 50% D. E. pumping of protons from the matrix of the mitochondrion to the intermembrane space. 0% Ans: A 118. All of the following are enzymes of the Krebs cycle EXCEPT A. how much of the original radioactivity will be found in the oxaloacetate formed after one turn of the cycle? A. B. succinyl-CoA synthetase C. 75% C. enolase. 25% E. succinic dehydrogenase D. pumping of electrons from the matrix of the mitochondrion to the intermembrane space. 100% B. Ans: C . isocitrate dehydrogenase Ans: D 117. B. The electron transport. Ans: A 116. which occurs at the inner membrane of the mitochondrion and leads to the synthesis of ATP. FoF1-ATPase Ans: A 115.C. pumping of protons from the intermembrane space into the matrix of the mitochondrion. Which enzyme of the Krebs cycle requires free coenzyme A as a substrate? A. results in which of the following processes? A. If acetyl-CoA. isocitrate dehydrogenase. succinate dehydrogenase D. pumping of electrons from the intermembrane space into the matrix of the mitochondrion. alpha-ketoglutarate dehydrogenase. succinate thiokinase. D. citrate synthase B. uniformly labeled with 14C in the acetyl group. succinate dehydrogenase. alpha-ketoglutarate dehydrogenase E. 2 rRNAs. provide reducing equivalents. Which type of enzyme can supply the citric acid cycle with oxaloacetate from pyruvate? A. large increase in internal bond energy. increase in the equilibrium constant. lower the oxidation state of the cell. E. generate a P/O ratio of 3. decrease in resonance. Mitochondrial genes code for 13 proteins. there is a(an) A. D. cytochrome c reductase C. Succinate dehydrogenase E. large decrease in free energy content between reactant and products. an isomerase B. a mutase C. B.119. a lyase Ans: C 122. lowering of the redox potential. C. For which multisubunit protein do these genes encode the most proteins? A. Ubiquinol-cytochrome c oxidoreductase Ans: C . The main function of the mitochondrial electron transport chain is to A. C. NADH-ubiquinone oxidoreductase D. When a high energy compound undergoes hydrolytic cleavage. E. Ans: E 121. a kinase E. and tRNAs. ATP synthase B. Ans: D 120. generate energy for ATP formation. a ligase D. D. recycle NAD for glycolysis. B. C. glycogen. C. pyruvate carboxylase. NADP. pyruvate dehydrogenase B. Biotin participates in the reaction catalyzed by A. B. B. glycogen phosphorylase E. isomerase C. phosphatase D. kinase B. pyruvate carboxylase C. Ans: B 4.fasting subject is most likely to produce a deficiency of A. The activity of which enzyme would be expected to increase as levels of insulin increase? A. D. mutase E. PEP carboxykinase Ans: A 2. E. Lack of activity of hepatic phosphoglucomutase in a non. dehydrogenase Ans: B . E. Ans: E 3. pyruvate dehydrogenase. phosphoenolpyruvate carboxylase kinase. glucose 6-phosphatase D. Which of the enzymes below acts in the conversion of glucose -6-phosphate to fructose -6-phosphate? A. lactate dehydrogenase. pyruvate. pyruvate kinase. D. ribose 5-phosphate. NADH.Chapter 15 Carbohydrate Metabolism I: Major Metabolic Pathways and Their Control Multiple Choice 1. NAD. ornithine B. dihydroxyacetone phosphate. All of the following are involved in some aspect of galactose metabolism EXCEPT A. Which of the following compounds is a key intermediate in gluconeogenesis from lactate. ATP. alanine. Ans: C 6. B. C. The net products of anaerobic glycolysis are A. B. a pyrophosphorylase. malonyl-CoA Ans: D 9. In the glycolytic pathway for conversion of glucose to lactate. ATP. oxaloacetate E. and glutamic acid? A. acetyl-CoA . glucose 1-phosphate phosphatase. fructose 2. pyruvate. 1.5. ligase C. isomerase Ans: A 8. D. Ans: D 7. UDP-glucose. pyruvate C. citrate C. lactate D. C.6-bisphosphate. lyase E. fructose 2-phosphate. lactate B. E. 3-phosphoglycerate. an immediate product of the reaction catalyzed by aldolase is A. ATP. D. E. a uridyltransferase. hydrolase D. an epimerase. acetyl-CoA D. transferase B. Glycogen phosphorylase catalyzes the following reaction Inorganic phosphate + glycogen (n) -->glucose -phosphate + glycogen (n-) To which enzyme class does it belong? A.3-diphosphoglycerate. pyruvate carboxylase. glucose 6-phosphatase. C. D. oxaloacetate and GTP. B. E. NADH E. citrate synthase. D.Ans: A 10. oxaloacetate and ATP. AMP. NADP D. D. Ans: E 14. The substrates for the phosphoenolpyruvate carboxykinase reaction are A. E. D. the active. B. B. phosphodiesterase. dephosphorylated form of glycogen synthase. pyruvate. ribose 5-phosphate C. pyruvate dehydrogenase. Ans: D 13. glycogen Ans: E 11. An enzyme catalyzing an anaplerotic reaction is A. phosphorylation of certain amino acids of phosphorylase kinase. B. Ans: C 12. E. the inactive. alanine and GTP. phosphorylated form of phosphorylase. thiolase. Epinephrine stimulates the formation of A. C. formation of cyclic AMP. A deficiency of hepatic phosphoglucomutase would most likely lead to a deficiency of which one of the following cellular components A. B. C. . hexokinase. Which of the following reactions IS NOT INVOLVED in regulation of the phosphorylase kinase cascade? A. C. proteolysis. phosphatases. phosphoenolpyruvate and GTP. activation of protein kinase. Which metabolic process is most markedly impaired in the ABSENCE of insulin? A. transport carbons and nitrogen from skeletal muscle to the liver. Transport of glucose through the muscle cell membranes. fructose 6-phosphate C. B. Ans: E 19. pyruvate and GTP. E. The substrate for the committed step in glycolysis is A. glucokinase. B. transport glucose from skeletal muscle to liver. The glucose-alanine cycle serves to A. fructose 2. . Ans: C 18. C. B. D. C. glycerol-3-phosphate E. Skeletal muscle glycogen is not a source of blood glucose because skeletal muscle does not contain A. Use of acetoacetic acid for energy. The malate-aspartate shuttle results in the reduction of intramitochondrial A. D.E. Ans: B 15. fructose 1. pyruvate. D. E.6-bisphosphate Ans: B 16. glucose 6-phosphate D. transport carbons and nitrogen from liver to skeletal muscle. glucose 6-phosphatase. glucose B. phosphoglucomutase. C. NAD. Ans: C 17. C. D. Degradation of glycogen to glucose. B. transport carbons from skeletal muscle to the liver. dihydroxyacetone phosphate. glucose 6-phosphate dehydrogenase. Reabsorption of glucose by the renal tubules. all of the above.6-bisphosphate E. transport nitrogen from liver to skeletal muscle. phosphorylase. glycolysis B. Cyclic AMP increases the intracellular concentration of calcium ions which stimulates the dephosphorylation of both glycogen phosphorylase and glycogen synthase. Which statement regarding the control of glycogen metabolism by cyclic AMP is TRUE? A. phosphofructokinase B. protein synthesis in muscle D. activating both. activating the former and deactivating the latter. Which enzyme is not subject to allosteric regulation? A. Cyclic AMP stimulates the phosphorylation of both glycogen phosphorylase and glycogen synthase. activating the former and inactivating the latter. Which process is NOT increased in the presence of insulin? A. hexokinase C. glycogen synthesis in muscle Ans: A . lipogenesis in adipose tissue E. gluconeogenesis in liver B. B. pyruvate kinase D. Hexose monophosphate shunt C. Cyclic AMP binds allosterically to both glycogen phosphorylase and glycogen synthase. Cyclic AMP stimulates the phosphorylation of glycogen phosphorylase and the dephosphorylation of glycogen synthase. C. Which of the following employs the enzyme phosphoenolpyruvate carboxykinase? A. glycogenolysis Ans: D 23. Krebs cycle D. activating the former and deactivating the latter.Ans: C 20. gluconeogenesis E. Cyclic AMP stimulates the phosphorylation of glycogen phosphorylase and glycogen synthase. E. glucose 6-phosphatase Ans: E 21. D. glucose transport into adipose tissue C. Ans: D 22. glycogen synthase E. mannose. A true statement concerning phosphofructokinase.6-bisphosphatase C. phosphofructokinase and pyruvate kinase B.6-bisphosphatase requires ATP for energy. glucose.6-bisphosphatase. fructose. All of the following enzymes have been shown to be defective in one of the glycogen storage diseases EXCEPT which one? A. E.24. fructose 1. PFK-1 is not found in red blood cells. Increased levels of ATP inhibit which pair of enzymes? A. maltose.(PFK-) and fructose-. pyruvate dehydrogenase and pyruvate carboxylase . C. D. All of the following sugars require the action of phosphofructokinase for their metabolism to carbon dioxide and water EXCEPT A. Two allosterically regulated enzymes on the pathway from lactate to glucose are A. phosphofructokinase and glucose 6-phosphate isomerase E. Ans: E 27. B. glucose 6-phosphatase B. PFK-1 catalyzes a reversible step in both glycolysis and gluconeogenesis. C. pyruvate carboxylase and fructose 1.6-bisphosphate is a positive allosteric regulator of PFK-1 and is a negative allosteric regulator of fructose-1.bisphosphatase is that A. B. phosphorylase D.6-bisphosphatase and glyceraldehyde 3-phosphate dehydrogenase D. Fructose-2. Ans: E 28. PFK-1 catalyzes the fastest step in glycolysis. glyceraldehyde 3-phosphate dehydrogenase and enolase B. branching enzyme (alpha-1. Fructose-1.6) Ans: B 26. galactose. glucokinase and phosphoglucomutase Ans: C 25.4 --> alpha-1. D. E. lactate dehydrogenase and triose phosphate isomerase C. pyruvate kinase C. phosphofructokinase and pyruvate kinase D. 6-bisphosphate D. galactose to glucose Ans: D 33. fructose 1-phosphate C. phosphorylase phosphatase. None of the above Ans: B 31. All of the following statements about glycolysis and gluconeogenesis are true EXCEPT which one? A. E. When citrate concentrations in the cytosol are high. C. fructose 1. UDP-glucose is intermediate in each of these conversions EXCEPT which one? A. fructose 6-phosphate B. phosphorylase kinase. Formation of glucose from glycerol does not require the involvement of mitochondria. cAMP. B. Ans: C 30. glycogen to glucose E. the action of fructokinase on fructose results in the production of A. In fructose metabolism in the liver. glucose to glycogen B. NADH2 is required for the formation of glucose from pyruvate. Phosphorylase is activated most directly by A.Ans: B 29. D. B. PFK-1 activity is inhibited and fructose-1. glucagon. D. E.6-bisphosphatase activity is stimulated. pentose 6-phosphate + carbon dioxide E. galactose to glycogen D. fructose to glycogen C. High concentrations of acetyl-CoA inhibit acetyl-CoA formation from pyruvate and high concentrations of acetyl-CoA stimulate carboxylation of pyruvate. Oxaloacetate is formed from acetyl CoA. C. Ans: B 32. epinephrine. Which one of the following molecules is a negative allosteric effector of phosphofructokinase? A. Succinic acid . Which is an unlikely metabolic fate of glucose--phosphate in muscle? A. Conversion to lactate. requires UTP. Hydrolysis to glucose. occurs in the mitochondrial matrix. E. Conversion to fructose-6-phosphate. glycogen synthase. E. phosphofructokinase D. is stimulated by a low energy charge. D. D. Ans: E 37. glucokinase B. C. C. Conversion to glucose-1-phosphate. phosphofructokinase. B.B. D. PEP carboxykinase C. The biosynthesis of glycogen from glucose –phosphate A. E. Ans: D 36. The activity of which enzyme is controlled by phosphorylation and dephosphorylation of serine residues? A. D. B. C. glucose 6-phosphatase. E. C. glycogen phosphorylase Ans: E 38. is catalyzed by glycogen phosphorylase. isocitrate dehydrogenase. ADP Oxaloacetate Citrate All of the above Ans: D 34. 3-phosphoglyceraldehyde dehydrogenase E. Ans: B 35. B. Binding of epinephrine to muscle cell receptors results directly in increased activity of A. Conversion to dihydroxyacetone phosphate and glyceraldehyde-3-phosphate. is stimulated by increased levels of cyclic AMP. adenyl cyclase. Which statement concerning phosphorylase is FALSE? . liver. B. D. The phosphorylation of phosphorylase increases at higher concentrations of cAMP Ans: C 39. Phosphorylation of phosphorylase in muscle is controlled by glucagon. The enzyme is activated by phosphorylation. C. kidney. C. B. phosphofructokinase. brain. The phosphorylation of phosphorylase is catalyzed by a protein kinase. The principal tissue involved in gluconeogenesis to provide glucose for the resynthesis of muscle glycogen following prolonged exercise is A. epinephrine. E.A. Ans: E 42. E. C. cortisol. thyroid hormones. Ans: E 41. an alpha-amylase. C.4 --> 1. C. The active enzyme catalyzes the reaction: (glucose)n + Pi -> (glucose)n-1 + Glucose1-P B. E. B. somatomedin A. Ans: C . glucose 6-phosphate dehydrogenase. an amylo (1. D. glyceraldehyde 3-phosphate dehydrogenase. Ans: B 40. The glycogen branching enzyme is classified as A. glucagon. D.6) D. D. B. heart muscle. skeletal muscle. Which enzyme uses inorganic phosphate as a substrate? A. E. glucokinase. E. a beta-amylase. glucose 6-phosphatase. The effects of insulin on glucose uptake by muscle tissue are most directly opposed by A. a uridine diphosphate glucose-glycogen glucosyl transferase. a glycogen phosphorylase. fructose-1.4 and beta-1. NADH is not oxidized.4 and alpha-1. glucose 1-phosphate and glucose C. Alpha-1.43. C. B. In glycogen.4-linkages only B. mitochondria are not present in the cell.4 linkages only D. B. UDP-glucose D. pyruvate carboxylase B. glucose-6-phosphatase D. being released from the pancreas in response to lowered blood glucose levels and then activating the liver phosphorylase system. Ans: B 44. the concentration of cAMP is decreased. E. Which liver enzyme is required to form glucose from both glycogen and lactate? A. Beta-1. D. activating adenylate cyclase in skeletal muscle cells. what types of linkages are present between the glucose units? A. glucose 6-phosphate and glucose E. phosphoglucomutase . UDP-glucose and glucose Ans: B 46. Glycolysis will cease if A. C. being released from the pancreas in response to elevated blood glucose levels and then activating the liver phosphorylase system. Beta-1.6 linkages E. D. Alpha-1.6 linkages C. phosphorylase a E. Ans: D 45. glucose 6-phosphate B. stimulating the release of glucose residues from muscle glycogen during periods of intense muscular activity. facilitating glucose uptake into skeletal muscle. Beta-1. The actions of glycogen phosphorylase and the debranching enzyme on glycogen results in which of the following product or products? A. Glucagon plays a homeostatic role by A. phosphofructokinase is activated.3 linkages Ans: D 47. 6-bisphosphatase C. ATP 3. glycogen synthase B. galactose and mannose. D.6-bisphosphate 5. 5 and 3 Ans: D 49. glycogen branching enzyme C. amylo-(1. Which of the following enzymes forms alpha-. The disaccharide lactose is composed of A. pyruvate kinase Ans: D 51. amylo-(1.6bisphosphate A.Ans: C 48. 1 and 3 B. glyceraldehyde-3-phosphate dehydrogenase E. aldolase B. enolase D. For which glycolytic enzyme is inorganic phosphate a substrate? A. phosphorylase kinase Ans: B 50. linkages in glycogen? A. glucose and glucosamine. Which of the following are activators of glycolysis AND inhibitors of gluconeogenesis? 1.fructose 2. glucose-6-phosphatase C.6) D. glycogen synthase B.6) D. glycogen branching enzyme C. phosphorylase kinase . 4 and 1 E. fructose 1. AMP 2. glucose and galactose.. glucose and fructose. E. C. Which of the following enzymes reactivates inactive liver phosphorylase? A. glucose and mannose. Ans: C 52. 2 and 4 C. B.citrate 4. 3 and 5 D. D. pyruvate kinase B. glucose-1-phosphate. C. E. Ans: D 54. The enzymes that catalyze the 3 irreversible steps of glycolysis are used in the process of glucose synthesis. The enzymatic reactions are carried out in 3 different subcellular compartments. D. ATP. AMP.6-biphosphate. For gluconeogenesis A.6-bisphosphatase and glucose-6-phosphatase D. ATP is not required. E. D. D. C. a decrease in the rate of electron transport and oxidative phosphorylation. A decrease in the ATP:ADP ratio would result in A. It occurs primarily in skeletal muscle. B. Ans: D 57. phosphoenolpyruvate dehydrogenase and pyruvate alpha_ketolase Ans: B 55. pyruvate dehydrogenase E. Which statement about gluconeogenesis is correct? A. glucose-6-phosphate. B. The following enzyme(s) is/are required to synthesize phosphoenol_pyruvate from pyruvate in gluconeogenesis: A. an increase in the net flux of intermediates through the glycolytic pathway. Glycogen phosphorylase P (the phosphorylated form) may be activated by A. E. none of the above Ans: C 56. No high energy phosphate compounds are involved. . a decrease of isocitrate dehydrogenase activity. pyruvate carboxylase and phosphoenolpyruvate carboxykinase C. Lactate and alanine can both serve as substrates. a decrease in phosphofructokinase activity. It occur through reversal of the reactions of glycolysis.Ans: D 53. B. B. The brain and testis are the most important tissues involved. Fructose-1. The acetate group of acetyl-CoA is used for the net synthesis of glucose. C. C. fructose-1. phosphoenolpyruvate carboxylase kinase. B. glucose 6-phosphate B.6-bisphosphatase and phosphofructokinase-1. pyruvate kinase. D. fructose 1. C. B. Ans: B 60. stimulates glucose transport into the liver.6-bisphosphate in liver. pyruvate kinase and phosphoglycerate kinase. it conserves the energy of an oxidation reaction as a high energy phosphate bond. . C. D. Ans: B 61.Ans: B 58. the enzyme forms a covalent high energy intermediate in the reaction. Which is a positive allosteric effector of phosphofructokinase? A. B. D. stimulates the phosphodiesterase enzyme which breaks down cAMP. citrate D. D. glyceraldehyde 3-phosphate dehydrogenase and aldolase. C. lactate dehydrogenase. ATP is a product of the reaction. E. Insulin A. B. phosphate is consumed in the reaction. has the same effect on glycolysis in the liver as glucagon. inhibits hepatic glycolysis. fructose 2. Two enzymes specifically required for gluconeogenesis from lactate but not from glycerol are A.6-bisphosphate E. acetyl-CoA C. pyruvate carboxylase and phosphoenolpyruvate carboxykinase. E. Biotin participates in the reaction catalyzed by A. E. decreases the concentration of fructose-2. Ans: A 62. NAD is required for the enzyme to function. E. pyruvate carboxylase C. glucose 6-phosphate dehydrogenase and phosphoenolpyruvate carboxykinase. ATP Ans: D 59. All the following statements about the enzyme glyceraldehyde -phosphate dehydrogenase are correct EXCEPT A. pyruvate dehydrogenase. C. hexokinase. pyruvate dehydrogenase. C.6 bisphosphate. Ans: D 67. glyceraldehyde 3-phosphate dehydrogenase. phosphofructokinase. B. fructose 1. B. Ans: C 65. is degraded in response to high glucagon levels. and phosphoenolpyruvate carboxykinase. An increase in glucagon will cause A. phosphofructokinase. an inactivation of liver adenyl cyclase. Galactokinase uses ATP as substrate. aldolase. E. hexokinase. A UDP-glucose molecule is an intermediate in galactose metabolism. 3-phosphoglyceraldehyde. Ans: C 64. Galactose is a ketose. E. 2-phosphoglyceric acid. Cyclic AMP A. a decrease in blood glucose. B. E. pyruvate kinase. B. hexokinase. D. B. has a phosphodiester bond between C-5 and C-2 carbons of the ribose moiety. modulates the level of fructose 2. Galactose is converted to glucose in the liver. an increase in muscle glycogenesis. D. D. A substrate which transfers phosphate directly to ADP is A.Ans: D 63. D.6-bisphosphate. and pyruvate kinase. E. 3-phosphoglycerate. phosphoenolpyruvate. . an increase in liver glycogenolysis. Ans: E 66. triose phosphate isomerase. hexokinase. All of the following statements about galactose and its metabolism are true EXCEPT: A. inhibits glucose-6-phosphatase. C. Digestion and absorption of lactose results in an increase in blood glucose concentrations. D. and lactate dehydrogenase. C. is synthesized directly from AMP. Glycolysis is only partially reversible because of energy barriers at the reactions catalyzed by A. and pyruvate kinase. C. an inhibited pyruvate dehydrogenase complex. The enzyme that catalyzes the conversion of fructose-l. an active form of pyruvate carboxylase. increased energy supply to the brain. acute stimulation of enzymes in the pathways of gluconeogenesis and glycogenesis. a low level of active phosphoenolpyruvate carboxykinase. hyperglycemia after a normal meal. D. C. Ans: D 71. what would best characterize the expected change in metabolism relative to the normal state? A. The likely mechanism of these effects involves A. If liver glucose -phosphatase were deficient. Ans: C 69. Ans: D 70. hypoglycemia one or two hours after a meal. such as promoting gluconeogenesis and glycogen deposition. a rapid rate of fatty acid oxidation. B. direct inhibition of enzymes participating in glycolysis and glycogenesis. C.-bisphosphate to fructose-phosphate + Pi is classified as A. All of the following metabolic conditions favor the conversion of pyruvate to glucose EXCEPT A. E. D. an energy charge near 1. binding of glucocorticoids to liver cell membrane receptors with concomitant activation of adenylate cyclase. D. depletion of glycogen stores in liver. B. C. D.Ans: A 68. a hydrolase. a transferase. a lyase. an oxidoreductase. B. a ligase. E.0. induction of new enzyme synthesis for enzymes in the pathways of gluconeogenesis and glycogen synthesis. C. Which of the following is an enzyme which catalyzes a freely reversible reaction under physiological conditions? . B. Ans: D 72. Glucocorticoids such as cortisol and corticosterone have distinct effects on hepatic carbohydrate metabolism. glucose 6-phosphatase phosphofructokinase aldolase phosphoenolpyruvate carboxykinase fructose bisphosphatase Ans: C 73. high levels of cellular ATP results in stimulation of this process. only one regulated enzyme is involved in the overall conversion of pyruvate to glucose. Adenylate cyclase is an enzyme which increases the concentration of the second messenger. 2. some of the enzymes of glycolysis participate in the conversion. D. glucose residues in an alpha 1-->6 linkage to the chain. cyclic AMP. C. 2-phosphoglycerate C. glyceraldehyde 2. All of the following statements concerning the conversion of pyruvate to glucose in mammals are true EXCEPT A. C. GTP is involved in this process. Ans: D 75. glucose residues in an alpha 1-->4 linkage to the chain. During the breakdown of glycogen.phosphate B. In the following pathway for conversion of glucose to pyruvate. electrons are shuttled from mitochondria to the cytoplasm during this conversion. E. E. C. conversion of glycogen synthase D to glycogen synthase I. D. Ans: E 76. hydrolysis of glucose 1-phosphate. D. E. . B. increased activity of a protein kinase. B. 1. D.3-bisphosphoglycerate D. increased conversion of phosphorylase a to phosphorylase b. increased conversion of carbohydrate into fatty acids. the reducing end. In liver high adenylate cyclase activity brings about A. B. B. 1-phosphoglycerate E. E. the non-reducing end.3-bisphosphoglycerate Ans: C 74.A. what is compound X? glucose --> --> --> --> glyceraldehyde -phosphate --> X --> phosphoglycerate --> -> --> pyruvate A. free glucose is formed from A. C. increased lipogenesis from gluconeogenic amino acids. Given ATP. B. Ans: E 78. The glycerol phosphate shuttle A. All of the following statements concerning gluconeogenesis are correct EXCEPT which one? A. calcium ions. epinephrine. One mole of glucose is produced from two moles of lactate. glyconeogenesis Ans: D 79. liver glycogenolysis E. results in production of dihydroxyacetone phosphate in the matrix of mitochondria. E.Ans: D 77. Which reaction is catalyzed by glycogen synthase? A. C. all the reactions of gluconeogenesis can occur in the absence of air. Ans: B 81. transfers electrons from cytosolic NADH to the respiratory chain of mitochondria. E. C. UDP glucose + glycogenin --> PPi + glycogenn+1 C. All of the following can stimulate the activity of muscle glycogen phosphorylase EXCEPT A. gluconeogenesis from lactate occurs in both mammalian liver and muscle. B. synthesis of carbohydrate from fat B. liver glycogenesis D. D. glycogenin + UDP-glucose --> glycogenn+1 + UDP E. D. glucagon. glucose 6-P + glycogenin --> Pi + glycogenn+1 Ans: D 80. supports phosphorylation of three moles of ADP per mole of cytosolic NADH oxidized. B. cyclic AMP. UTP + glucose 1-P --> UDP-glucose + PPi B. . uses 3-phosphoglyceric acid as a substrate. inhibits glycolysis. absorption of carbohydrate from the digestive tract C. What is the primary process by which epinephrine increases blood sugar? A. UDP glucose + glycogenin --> UMP + Pi + glycogenn+1 D. phosphorylase kinase. C. six molecules of ATP (or its equivalent) are required to synthesize one molecule of glucose from lactate. C. The first step for which ATP is required is catalyzed by phosphofructokinase. D. What change will occur when oxygen is introduced? A.D. Which of the following compounds is the direct glucosyl donor in the biosynthesis of glycogen in animal tissue? A. Ans: C 83. The rate of glycolysis in the absence of oxygen is usually less than the rate in the presence of oxygen. glycogen synthase C. Muscle cells are metabolizing glucose in the absence of oxygen. activation of phosphofructokinase .6-bisphosphate Ans: A 85. E. The action of phosphoprotein phosphatase would be expected to activate which of the following? A. adenosine diphosphate glucose E. The conversion of pyruvate to lactate requires NAD. glucose 1-phosphate D. glucose 1. increased accumulation of lactate D. Which statement about glycolysis is TRUE? A. Photosynthesis in green plants utilizes part of the gluconeogenic pathway for hexose synthesis. The phosphoglycerate kinase reaction is reversible under physiological conditions but the hexokinase reaction is not. thymidine diphosphate glucose C. phosphorylase kinase E. uridine diphosphate glucose B. decreased rate of utilization of glucose C. phosphorylase B. Ans: A 82. cAMP_dependent protein kinase Ans: B 84. increased rate of utilization of glucose B. B. Although a net of two molecules of ATP are generated per molecule of glucose converted to lactate. The product of the reaction catalyzed by triose phosphate isomerase is phosphoenolpyruvate. E. protein phosphatase inhibitor_1 D. 3 and 5 D. C. decreased activity of the Krebs cycle Ans: B 86. degradation of glycogen. Ans: C 87. The action of the enzyme phosphorylase kinase results in the A. amylose. glycolysis activity. succinyl-CoA synthase and phosphorylase b kinase. hexokinase and glycerol kinase. activity of phosphofructokinase. phosphoenolpyruvate carboxykinase and 3-phosphoglycerate kinase Ans: D 90. E. C. A rise in ATP/ADP ratio in liver tends to increase the A. B. B. activation of a protein phosphatase. Ans: D 88. activation of glycogen synthase. 1 and 3 B.E. maltose. C. phosphofructokinase and pyruvate kinase. 2 and 4 C. concentration of AMP. inactivation of glycogen phosphorylase. B. D. pyruvate kinase and 3-phosphoglycerate kinase. D. Galactose is found in the hydrolytic products of: A. E. E. 1 and 4 E. 2 and 5 Ans: E 89. inactivation of glycogen synthase. activity of gluconeogenesis. . Regulated steps in glycolysis of muscle tissue include which of the following? () the phosphohexose isomerase reaction () the phosphofructokinase reaction () the enolase reaction () the phosphoglycerate kinase reaction () the pyruvate kinase A. D. activation of glycogen phosphorylase. B. The two enzymes which catalyze the substrate-level phosphorylation of ADP to ATP in glycolysis are A. fructose 1. C & D Ans: E . The D form depends upon high intracellular levels of glucose 6-phosphate in order to be active. Which of the following type of cells are not dependent on insulin for glucose transport? A. catalyzes the synthesis of alpha-1. C. uses glucose 1-phosphate as a substrate. D. The D and I forms of the enzyme are interconvertible through phosphorylation and dephosphorylation. lactose. glucose 6-phosphatase. All of the following statements concerning glycogen synthase are true EXCEPT which one? A. Brain E. increased intracellular levels of glycogen inhibits the conversion of the D form to the I form. glycogen. B. PEP carboxykinase. Kidney D. Ans: D 92. Glycogen synthase A. PEP carboxykinase. B. glucose 6-phosphatase and aldolase A. D. C. D. when phosphorylated yields a more active form. Ans: C 94. requires a primer. Ans: D 93.6 glycosidic linkages. Enzymes in liver which are exclusively gluconeogenic are A. Skeletal muscle B. B. High intracellular levels of ATP can stimulate glycogen synthase D activity. fructose bisphosphatase and glucose 6-phosphatase. they are all true. D. catalyzes a freely reversible reaction. E. In skeletal muscle. Ans: C 91. E. fructose bisphosphatase. sucrose. C. None of the above. E.C.6-bisphosphatase and glucokinase. pyruvate dehydrogenase and PEP carboxykinase. Adipose tissue C. liver. glucagon decreases membrane permeability to fatty acids. fructose 1. Ans: A 97. 3-phosphoglyceraldehyde Ans: B 99. cAMP Ans: B 96. glucagon allosterically regulates many enzymes directly. Fructose-2. . Which of the following statements concerning the regulation of glycolysis and gluconeogenesis is FALSE? A. epinephrine E. glucose 1-phosphate C. glucagon stimulates a cAMP mediated cascade which results in the phosphorylation of one or more target enzymes. NADH and acetyl-CoA inhibit the formation of more acetyl-CoA. B. B. glucose 6-phosphate B. insulin stimulates glycolysis. Citrate inhibits gluconeogenesis. Which directly stimulates the activity of glycogen synthase D? A. E. kidney. C. B. D. adipose tissue. AMP B. D. C. E. muscles. glucagon decreases membrane permeability to glucose. Which of the following statements best describes the mechanism for glucagon's control of metabolism? A. glucagon inhibits glycolysis in the liver but not in skeletal muscle. D. E. glucose 6-phosphate C.6-bisphosphate E. The main organ responsible for keeping the blood glucose level steady between meals by making glucose via gluconeogenesis is the A. Ans: C 98. ATP D. glucagon decreases the synthesis of glycolytic enzymes. C. fructose 6-phosphate D. Which is NOT an obligatory intermediate in the anaerobic glycolysis of glucose? A.6-bisphosphate stimulates glycolysis. pancreas.95. citrate lyase C. The fully functional enzyme has more than one active site. fructose 1. The b form contains a phosphorylated serine group. fructose Ans: E 103. phosphoenolpyruvate carboxykinase. D. Its activity is increased by high levels of AMP. Two allosterically regulated enzymes on the pathway from lactate to glucose are A. galactose. B. pyruvate dehydrogenase and pyruvate carboxylase Ans: B 104. lipoprotein lipase Ans: C 101. lactate dehydrogenase E. E. Glucagon secretion would be most likely to lead to the elevation of which one of the following enzymes? A. phosphoenolpyruvate carboxykinase D. glucose.Ans: C 100. All of the following statements apply to skeletal muscle glycogen phosphorylase EXCEPT which one? A. glucose. A. 3-hydroxy-3-methyl glutaryl CoA reductase E. pyruvate carboxylase and fructose 1. Ans: C 102. D. fructose 1. glucose C. fructose. The activity of the liver enzyme is influenced by levels of epinephrine. pyruvate kinase. C. glucose B.6-bisphosphatase. fructose D. acetyl CoA carboxylase B.6-bisphosphatase and glyceraldehyde 3-phosphate dehydrogenase D. galactose. fructose E. Acetyl-CoA regulates gluconeogenesis by activating A. pyruvate carboxylase. Sucrose is a disaccharide composed of __ linked to__ . phosphofructokinase and pyruvate kinase B. . B. Phosphate ion is one substrate of this enzyme. C.6-bisphosphatase C. fructose 6-phosphate C. Fructose . stimulation of a phosphoprotein phosphatase. Ans: D 108. competitive inhibitor. fructose 1. activation of a protein kinase. The earliest consequence of an increase in the level of cyclic AMP in muscle cells will be A. All of the following would be caused by or would be the result of increased levels of epinephrine in the circulatory system EXCEPT A. production of cyclic-AMP. In the carboxylation of pyruvate to oxaloacetate by the enzyme pyruvate carboxylase.-bisphosphate stimulates A. inhibition of phosphodiesterase. E. glucokinase D. stimulation of adenylate cyclase. phosphorylation in liver cells of side-chain of specific serine units of certain proteins.Ans: D 105. C. C. phosphoenolpyruvate carboxykinase Ans: E 106. malate dehydrogenase D. substrate. Ans: D 107. C. phosphofructokinase-1 Ans: D 109. D.6-bisphosphatase B. B. pyruvate kinase E. . acetyl CoA interacts with pyruvate carboxylase as a A. B. pyruvate dehydrogenase B. phosphorylation of phosphorylase b kinase. D. homotropic activator. heterotropic activator. D. dissociation of the catalytic subunit of protein kinase from the regulatory subunit. noncompetitive inhibitor. E. An enzyme required for gluconeogenesis and which uses GTP as a substrate is A. pyruvate carboxylase C. increased breakdown of liver glycogen. B. 6_bisphosphate D. None of the above is correct. The conversion of UDP-galactose to UDP-glucose involves A. E. Ans: C 110. ATP B. Enzymes catalyzing reactions that are essentially irreversible under physiological conditions include A. Ans: B 112. aldolase. Formation of ATP and pyruvate occurs since under intracellular conditions the hydrolysis of ATP is exergonic while the hydrolysis of phosphoenolpyruvate is endergonic. B.6_bisphosphate Ans: C 113. B. C. citrate C.E. a mutase. D. Ans: D . C. Reaction is an example of oxidative phosphorylation. phosphopentose isomerase. C. an isomerase. Concerning the reaction Phosphoenolpyruvate + ADP -----> pyruvate + ATP which of the following statements is true? A. E. phosphoglycerate kinase. an epimerase. Which of the following would stimulate the principal controlled step of glycolysis? A. a dehydrase. increased rate of glycogen breakdown. fructose 2. Ans: C 111. B. Formation of ATP and pyruvate occurs since hydrolysis of phosphoenolpyruvate results in the release of free energy that is numerically larger than the free energy associated with the phosphorylation of ADP E. more than one of the above. Reaction equilibrium lies far to the left. an aldolase. glucose 6_phosphate E. D. fructose 1. hexokinase. D. 114. B. Glycogen in muscle A. D. C. serves primarily as a buffer of blood glucose levels. 4 Ans: D 115. fructose 6_phosphate. Ans: E 117. transfer of a chain of three glucosyl residues. serves as a source of fuel for ATP synthesis within that tissue. Using a signal transduction pathway. serves as a source of glucose-6-phosphate which is subsequently dephosphorylated by glucose-6-phosphatase and transported out of the cell. glucose 6-phosphatase. fructose 2. breakage of alpha-1. all of the above Ans: E 118. released from glycogen. breakage of alpha-1. C. 3 E. D. pyruvate carboxylase. B.6_bisphosphate. is rapidly depleted during fasting. B. C.6_bisphosphate. Which characterizes the activity of (glycogen) debranching enzyme? A. 2 D.6-bisphosphatase. phosphoenolpyruvate (PEP)-carboxykinase. Ans: A 116. fructose 2_phosphate.4-bonds B. E. 1 C. glucagon influences the activity of the enzyme that catalyses the formation of A. D. D. production of free glucose E. pyruvate dehydrogenase. All of the following are gluconeogenic enzymes EXCEPT A. What is the approximate yield of ATP (from ADP) when one residue of glucose. E. is converted to lactic acid under anaerobic conditions? A.6-bonds C. fructose 1. fructose 1. fructose 1_phosphate. 0 B. Ans: E . two molecules of GTP and eight molecules of ATP. B.119. ATP. pyruvate carboxylase. E. lactate. B. modulates oxygen binding by hemoglobin. lactate. is elevated in pyruvate kinase deficiency. The formation of one molecule of glucose from pyruvate in liver requires as substrates A. Ans: C 120. is inactive but can be allosterically stimulated by AMP. acetyl-CoA. ATP. is inactive but can be allosterically stimulated by glucose 6-phosphate. Ans: C 121. ATP. pyruvate. phosphorylates 6-phosphofructo-1-kinase. it A. E. C. allosterically inhibits hepatic gluconeogenesis. E. D. acquires a phosphate group on a tyrosine residue. The NET products of anaerobic glycolysis are A. pyruvate. two molecules each of GTP and ATP. D. NAD. NAD. two molecules of GTP and four molecules of ATP. E. An enzyme required for gluconeogenesis from lactate and which uses ATP as a substrate is A. C. ATP. uncouples oxidative phosphorylation. . pyruvate kinase. When glycogen synthase is phosphorylated. one molecule of GTP and two molecules of ATP.-bisphosphate A.6 bonds between glucose molecules. malate dehydrogenase D. catalyzes synthesis of alpha-1. one molecule each of GTP and ATP. Ans: B 122. D. NADH. C. C. ATP. D. pyruvate dehydrogenase. is active in the synthesis of glycogen from UDP-glucose. Fructose-. C. phosphoenolpyruvate carboxykinase. B. B. B. Ans: A 123. E. contains phosphorylated serine residues. Phosphorylase b Ans: E 126. inhibit phosphofructokinase-1. decreasing FAD in liver. C. . B. Phosphorylase a A. direct activation of glucose 6-phosphatase. C. stimulate glycogen synthase D.Ans: D 124. competition with lactate for NAD. Adenylate cyclase B. B. phosphofructokinase E. inhibition of pyruvate dehydrogenase. inhibition of fatty acid oxidation. C. E. Ans: B 127. Ethanol may inhibit gluconeogenesis by A. Which of the following participates in sugar transfer reactions in man? A. The hepatic sensor of blood glucose levels is: A. UDP-beta-D-glucose B. GDP-beta-D-mannose D. is activated directly by cyclic AMP. stimulate hexokinase. stimulate phosphorylase. Calmodulin C. is the less active form of the enzyme. exists as a dimer. none of the above Ans: A 125. High concentrations of glucose—phosphate A. GDP-alpha-D-galactose Ans: B 128. UDP-alpha-D-mannose E. UDP-alpha-D-glucose C. B. Fructose bisphosphatase D. D. E. D. D. stimulate glucokinase. E. B. B. E. phosphorylation at C-1. glucagon and epinephrine. Ans: C 131. D. fructose 6-phosphate. Ans: C 133. It adenylates inactive phosphorylase converting it to an active form. high concentration of fatty acyl CoA in the cytosol C. B. . It allosterically activates an enzyme which initiates a series of reactions resulting in the activation of phosphorylase. C. It allosterically activates the phosphorylase. high concentration of fructose-2. The immediate precursor of mannose phosphate is A. E. Gluconeogenesis is stimulated by A. E. C. glucagon and norepinephrine. It phosphorylates an enzyme which initiates a series of reactions resulting in the activation of phosphorylase. AMP (cyclic AMP) activates glycogen phosphorylase by which mechanism? A. increase in the amount of the enzyme glucokinase Ans: A 132. oxidation at C-6. glucose 6-phosphate. D. It allosterically inhibits phosphorylase phosphatase. mannose 1-phosphate. B.6-bisphosphate in the cytosol E. C. high concentration of acetyl CoA in the mitochondria B. fructose 1-phosphate. Mannose is made in the body from glucose. epinephrine and somatostatin. Ans: B 130. The immediate event that occurs to glucose on entering a liver cell that prevents the glucose from escaping the cell is A. Which of the following stimulates gluconeogenesis? A. D. C. UDP-mannose.129. polymerization into glycogen. insulin D. D. phosphorylation at C-6. insulin and glucagon. conversion into galactose. phosphofructokinase. Synthesis of carbohydrate from fat B. AMP stimulates PFK-1. E. glucokinase E. The most important enzyme in the physiological regulation of glycolysis is A. C. . aldolase C. enolase B. Fructose 1. C.Ans: D 134.6-bisphosphate stimulates PFK-1. B. glucose 6-phosphate dehydrogenase. D. Liver glycogenolysis E. B. All of the following mechanisms govern the activity of phosphofructo. There cannot be significant net formation of glucose from stearic acid in a mammal because of the irreversibility of the reaction catalyzed by A. hexokinase. pyruvate dehydrogenase. Absorption of carbohydrate from the digestive tract C. D. pyruvate kinase. glucose 6-phosphatase Ans: E 136. Ans: D 138. ATP inhibits PFK-1.kinase(PFK-) EXCEPT A. Citrate inhibits PFK-1. B. hexokinase. E. Ans: A 135. C. hexosephosphate isomerase. Liver glycogenesis D. The increase in blood sugar level resulting from epinephrine injection can best be explained by which one of the following? A. Fructose 2.6-bisphosphate stimulates PFK-1. fructose 1. pyruvate carboxylase.6-bisphosphatase D. gluconeogenesis Ans: D 137. The Cori cycle is important as a consequence of the lack of which of the following enzymes in muscle? A. C. B. It does not require Mg++. B. There are two ATP-binding sites on the enzyme.6-bisphosphate is forced toward completion because standard free energy for the reaction is negative. glucose. It is found in liver.D. ATP is the phosphate donor and also inhibits phosphofructokinase. E. B. E.-bisphosphate. Glucuronic acid is synthesized most directly from A. Liver C. At high ATP levels. C. Adipose tissue B. D. triose phosphate isomerase. You have just been awarded a grant to study the relationship of glycogen metabolism to blood glucose levels in laboratory rats and are planning your first experiments. ascorbic acid. Which statement is true of glucokinase? A. None of the above is correct. The enzyme is shut down only at high ATP concentrations when the energy charge is high. Kidney E. a catalytic site with low affinity and a regulatory binding site with high affinity. Which of the following tissues would be the most critical to include in your study? A. UDP-glucose. Skeletal muscle D. Ans: C 140. C. galactose. E. a catalytic site with a high affinity for ATP. gluconolactone. aldolase. The formation of fructose 1. There are two ATP-binding sites on the enzyme. It catalyzes the phosphorylation of fructose. Ans: C 139. D. It has a lower Km for glucose than does hexokinase. . the enzyme is inhibited fully. How can ATP act as a substrate and as a feedback inhibitor? A. Bone marrow Ans: B 142. and a regulatory site with low ATP affinity. Phosphofructokinase catalyzes the phosphorylation of fructose -phosphate to form fructose . Ans: C 141. C. B. stearic acid A. glucose 6-phosphate dehydrogenase. oxaloacetate . 1 and 3 B. 3-Phosphoglyceraldehyde dehydrogenase. G6P is a feedback inhibitor of the enzyme. When epinephrine binds to its receptor on skeletal muscle. D. acetoacetate . even after ATP is unbound. adenylate cyclase. cyclic AMP-dependent protein kinase. Thus a high ATP concentration inhibits the reaction. glycogenolysis is stimulated. One form of glycogen synthase has a requirement for glucose -phosphate (GP). cytoplasmic malate dehydrogenase. 2 and 4 C. binding ATP lowers the probability of reaction for a short time. debranching enzyme. G6P is required for activation of the enzyme by cAMP. C. B. This is because A. none of the above Ans: C 143. G6P is an allosteric activator of glycogen synthase. G6P is a substrate for the enzyme. D. G6P is a substrate for branching enzyme. 2 and 3 Ans: B 145. Ans: D 144. E. B. . C. E. 4 and 5 E. The hormone signal influences the activity of each of these enzymes EXCEPT A. pyruvate . alpha-glycerol phosphate dehydrogenase. E. lactate dehydrogenase. D. There is a single ATP-binding site. acetyl CoA .D. Ans: E 146. E. phosphorylase kinase a. Oxidation of NADH produced in the cytoplasm can be catalyzed by all EXCEPT A. Net gluconeogenesis (the net synthesis of glucose) can be carried out using which of the following metabolic intermediates as a starting material? . 3 and 5 D. phosphorylase. phosphoenolpyruvate + ADP <----> pyruvate + ATP. fructose 1. C. heart muscle C. Which of the following would you predict? A. C. palmitic acid.6-bisphosphate. decreased rate of glycolysis and increased rate of gluconeogenesis D. You are studying a patient with an unusual metabolic defect resulting in abnormal glucose metabolism. cardiac muscle. connective tissue. D. How many moles of ATP (or equivalent) are required for the reactions through which lactic acid is converted to a mole of glucose in the liver. decreased rate of gluconeogenesis Ans: C 148. Adipose. E. Ans: E 150. C. Ans: B 149. increased rate of glycolysis B. muscle. alanine. B. nervous tissue Ans: B 151. 6. decreased rate of gluconeogenesis and increased rate of glycolysis C. ATP. pancreas D. D. 4. skeletal muscle. E. Which of the following tissues utilize insulin_dependent (GLUT) transporters for glucose uptake? A. The reaction that is common to both the breakdown and the biosynthesis of glucose is A. All of the following are negative modulators of liver pyruvate kinase EXCEPT A. A. small intestine B. glucose + ATP < ---> glucose-6-phosphate + ADP. 2.Ans: E 147. . You have determined that the patient has very low levels of phosphofructokinase_ and fructose . Skeletal muscle. fructose 6-phosphate + ATP <----> fructose 1. 3. B. B. 5. Liver. Brain. oleic acid._bisphosphate.6-bisphosphate + ADP. Reduction of cytosolic oxaloacetate to malate. aldolase. B. phosphoglucomutase and UDP-glucose pyrophosphorylase C. citrate synthase. E. pyruvate kinase D. fructose 1. reduction of NAD+ to NADH. The reducing equivalents of cytosolic NADH derived from glycolysis can be utilized for the mitochondrial electron transport system by A. Ans: C 155.3-bisphosphoglycerate + ADP <----> 3-phosphoglycerate + ATP. phosphofructokinase C. Direct reduction of FAD by NADH by mitochondrial glycerol_3_ phosphate dehydrogenase.6-glucosidase . and donation of electrons from NADH to complex I. C. Which pair of enzymes participates in the synthesis of glycogen from glucose? A. which enzyme must be present in addition to the glycolytic enzymes? A. E. D. E. and donation of electrons to complex I. transport of phosphatidyl glycerol into the mitochondrial matrix. 1. hexokinase. An enzyme in the glycolytic pathway that results in the conversion of hexosebisphosphate into triose-phosphates is A.D. Transport of NADH into the mitochondrial matrix and donation of electrons to electron transport complex I. amylase and amylo-1. During gluconeogenesis. glycogen phosphorylase and amylo-1. B. pyruvate dehydrogenase E. Ans: D 152. Direct donation of electrons to cytochrome c in the intermembrane space. D. reoxidation of malate to oxaloacetate and reduction of NAD+ to NADH. glucose 6-phosphate + water <----> glucose + Pi. C. triose isomerase.6-bisphosphate phosphatase B. pyruvate kinase. glyceraldehyde 3-phosphate dehydrogenase Ans: A 153. Ans: E 154.6-glucosidase B. transport of malate into the mitochondrial matrix. Reduction of dihydroxyacetone phosphate to phosphatidyl glycerol. glycogen synthase and glycogen phosphorylase D. in the liver. E. 0 B. decrease in blood glucose. increase in fructose 2. E.6_bisphosphate. enters directly into glycolysis mainly as fructose-6-phosphate. glucokinase D. must be isomerized into glucose-6-phosphate before it can be metabolized. binding to phosphorylase. What is the net yield of NADH when glucose -6-phosphate is converted to lactate by anaerobic glycolysis? A. pyruvate carboxylase C.E. 3 E. inhibiting glycogen synthase. Which enzyme would be expected to increase in activity on administration of insulin? A. PEP carboxykinase Ans: C 159. glycogen phosphorylase E. increase in muscle glycogenesis. there is a concomitant A. 2 D. C. 1 C. activation of liver adenylate cyclase. catabolism in liver requires the action of a special aldolase that recognizes fructose-1phosphate. D. 4 Ans: A 160. B. Ans: C 157. unlike glucose.6-bisphosphate phosphatase B. Insulin promotes glycogen synthesis in the liver by: A. As blood levels of glucagon increase. C. glucose 6-phosphatase and phosphoglucose isomerase Ans: B 156. . is converted into UDP-fructose and then epimerized into UDP-glucose. D. fructose 1. Fructose A. decrease in liver glycogenolysis. B. B. Ans: E 158. cannot be metabolized by any part of the glycolytic pathway. activating phosphorylase.C. causing the dephosphorylation of both phosphorylase and glycogen synthase. E. D. Ans: C . facilitating the transport of glucose into the cell. Chapter 18 Lipid Metabolism II: Pathways of Metabolism of Special Lipids Multiple Choice 1. glycerol 3-phosphate ==> PA ==> 1. glycerol ==> glycerol 3-phosphate ==> PA == 1. B. none of the above. Ans: C 2. C. Which of the following is the most correct sequence involved in the synthesis of triacylglycerols (triglycerides) in the fat cell? A. Most of the cholesterol in serum is contained in LDL as unesterified cholesterol.2-DG ==> PA ==> TG E. The density of a lipoprotein increases as the ratio of lipid to protein in the particle increases. Free unesterified choline reacts with a diglyceride to form phosphatidyl choline. C. E. Most of the triglyceride in serum is contained in VLDL and chylomicrons. D. C. phospholipase C Ans: A 4.2-DG ==> TG Ans: A 3. Which of the following statements about the synthesis of phospholipids is TRUE? A. Which of the following statements concerning the serum lipoproteins is true? A. phosphatidyl alanine is hydroxylated to form phosphatidyl serine. diacylglycerol lipase. D. PA ==> glycerol 3-phosphate ==> 1. 5-lipooxygenase. Both aspirin and indomethacin block prostaglandin formation by inhibition of A. E. D. cyclooxygenase B. phospholipase A2. glycerol 3-phosphate ==> 1.2-DG ==> TG C.2-DG ==> TG B. B. Ans: A . Fatty acids are added to phospholipids as CDP-fatty acids. glycerol 3-phosphate ==> MG ==> DG ==> TG D. phosphatidyl ethanolamine is methylated to phosphatidyl choline by S-adenosyl methionine. The chylomicron particle is smaller than the LDL particle. . The uptake of LDL into a cell by the LDL receptor does all of the following EXCEPT A. E. a phospholipase C . glycerol phosphate. none of the above. phosphatidic acid.5. B. B. adipolytic lipase. Ans: B 8.like enzyme. D. none of the above possibilities. B. Niemann Pick disease results from a deficiency of A. squalene. and choline. and phosphate. presqualene pyrophosphate. stimulates cellular acyl-CoA:cholesterol acyltransferase (ACAT). Ans: E 7. Phosphatidate phosphatase is involved in the synthetic pathway for A. triglycerides. E. D. 3.3-dimethylallyl pyrophosphate. farnesyl pyrophosphate. acylceramide and phosphate. Ans: B 6. C. a fatty acid. are A. ceramide phosphate and choline. ceramide and phosphorylcholine C. lipoprotein lipase. choline. D. ceramide. inhibits hydroxymethylglutaryl-CoA (HMG-CoA) reductase. Ans: D 9. E. choline. C. pancreatic lipase. D. E. The products of the hydrolysis of sphingomyelin by sphingomyelinase. Geranyl pyrophosphate condenses with isopentenyl pyrophosphate to form A. ceramide. cholesterol. B. sphingomyelinase. B. C. E. increases cholesterol esterification. decreases the rate of synthesis of the LDL receptor. is a product of cholesterol catabolism. phosphatidate phosphohydrolase is required Ans: E 12. is a complex fatty acid which accumulates in Refsum's disease. is a hydrocarbon that may undergo attack by oxygen to form an epoxide. medium chain non-esterified fatty acids via the lymphatic system. Apo C-III. Apo A-I. Lipoprotein lipase is . In the cell. Apo E. D. Ans: D 13. B. none of these. Apo C-II. E. Apo B-100. D. B. C. non-esterified fatty acids to the adipose tissues. triacylglycerol from the liver to the adipose tissues. Capillary lipoprotein lipase is activated by A. C.5'-cyclic AMP is inhibitory E. Ans: E 10. Ans: B 14. non-esterified fatty acids to the liver. S-adenosylmethionine is required C. The non-phosphorylated form of glycerol phosphate acyl transferase is required D. Very low density serum lipoproteins transport A. D. is found only in sharks of the genus Squalus. D. E. E. Absence of 3'. CTP is required B. C. converts LDL to HDL and HDL remnants.C. is a steroid which is a cholesterol precursor. B. Ans: A 11. All of the following statements on the biosynthesis of phosphatidylcholine (lecithin) in mammalian adipose tissue are correct EXCEPT which one? A. squalene A. including gangliosides. D. C. Ans: A 18. B. . thromboxanes. Ans: D 16. E. C. The different polar head groups are attached to the hydroxyl group (position 1)of the sphingosine base. catalysis by peroxisomal enzymes. prostacyclins.A. hormonal regulation by glucocorticoids. E. cholesterol conversion to bile salts involves shortening of the side chain of cholesterol. D. The sphingosine base is attached via an amide linkage to a saturated or monounsaturated fatty acid. C. D. feedback regulation by ceramide. A characteristic feature common to the degradation of most sphingolipids. It has two nonpolar tails. stimulated by cAMP. D. A pharmacological dose of a non-steroidal anti-inflammatory agent would not inhibit the synthesis of A. the stimulus for mobilization of stored triglycerides from adipose tissue. catalysis by lysosomal enzymes. stimulated by epinephrine. B. leukotrienes. F-series prostaglandins. Ans: D 15. C. Ans: C 17. E. is A. participation of nucleotide intermediates. an intracellular enzyme. In the metabolism of cholesterol in the human A. B. All of the following are true about a ceramide EXCEPT which one? A. B. E-series prostaglandins. They are found in highest concentration in depot fat. stimulated by one of the apolipoproteins found in VLDL. glucose. glycocholate. biotin. most of the reactions take place in the mitochondria. cholecalciferol (Vitamin D3) Ans: A 21. E. Which group of molecules appropriately combined would form lecithin? A. D. Ans: B 23. sphingosine. B. prostacyclin. E. cholesterol can be oxidized to carbon dioxide and water. glycerol. C. sphingosine. two fatty acids. phosphatidic acid and CDP-choline. fatty acid. N-acetylgalactosamine. phosphoric acid. C. phosphoric acid. The enzyme that condenses serine and palmitoyl-CoA to form -dehydrosphinganine requires A. vitamin B12. Phosphatidylcholine is synthesized by the reaction of A. glucose. retinal. fatty acid E. two fatty acids. pyridoxal phosphate. Cholesterol serves as a precursor for each of the following EXCEPT A. pregnenolone. glycerol. Nacetylgalactosamine D. . choline C. Ans: D 20. B. glycerol. cholesterol is synthesized only in the liver. D. D. B. In the synthesis of cholesterol A. ethanolamine Ans: B 22. phosphoric acid. niacin. only the methyl group of acetyl CoA is incorporated. C. choline. phosphoric acid. phosphoric acid. N-acetylneuraminic acid. C. dietary cholesterol has no influence on the rate. the adrenal gland is the only tissue which is active.B. plasma cholesterol is entirely in the form of cholesterol esters. E. plasma cholesterol readily exchanges with the brain cholesterol. two fatty acids B. Ans: A 19. mevalonic acid formation seems to be the controlling step. D. acetoacetate. Treatment of phosphatidylcholine with which enzyme would be most likely to liberate arachidonic acid? A. 1-palmitoyl-sn-glycerol-3-phosphate and CDP-choline. E. Ans: A 25. D. The initial catalytic steps in the synthesis of cholesterol from acetyl-CoA are utilized by the pathway producing A. B. Chylomicrons: A. A. D. phospholipase D. phospholipase A1. Ans: B 26. lysolecithin and CDP-choline. citrate. are secreted into the blood directly from the intestine. .5 trisphosphate B. C. C. Ans: E 24. ceramide. D. C. E. arachidonic acid E. D. A precursor of leukotrienes. B. C. 1-palmitoyl-sn-glycerol and CDP-choline. palmitate. phospholipase C. have more phospholipid than HDL. inositol 1.B. are smaller than HDL. mainly carry dietary triglycerides. diacylglycerol and CDP-choline. require the action of LDL for absorption. cholera toxin D. phospholipase A2. cAMP Ans: D 27. diacylglycerol C.4. B. serine E. E. hydrolyze cholesterol esters in preparation for receptor-mediated endocytosis. Ans: C 30. FADH2 C. D. NADH E. 7-alpha-hydroxylation. . activate lecithin-cholesterol acyl transferase. B. Pyridoxal phosphate Ans: C 31. squalene B. The second step of prostaglandin synthase converts PGG 2 to PGH2. spermine C.E. The rate-limiting step in the conversion of cholesterol to bile acids is A. Biopterin B. 12-alpha-hydroxylation. sorbitol Ans: D 32. What is the cofactor for this reaction? A. Ans: D 29. C. side chain oxidation. Prostaglandins are inactivated A. An established function of one of the apolipoproteins in the LDL particle is to A. disrupt the gel network preventing lysosomal budding. primarily in the liver. Ans: A 28. coat pits in the plasma membrane with its cage-like structure. provide a recognition marker for binding to the LDL receptor. C. B. serotonin D. E. D. ribulose 5-phosphate. conversion to coprostanol. Glutathione D. 7-beta-hydroxylation. Which of the following is directly involved in the biosynthesis of sphingosine? A. phosphatidylcholine participates in the synthesis of sphingomyelin by providing A. sphingosine and serine. by conversion to thromboxanes. Ans: A 36. C. LDL E. chylomicrons B. sphingosine and fatty acid. B. in the presence of molecular oxygen. only in the circulation. sulfatide Ans: C 34. glycerol and fatty acid. D. D. Ans: D 33. E. glucocerebroside. VLDL C. a fatty acyl group. an acylglycerol group. A ceramide is composed of A. HDL Ans: E . by oxidation of the 15 hydroxy group by a prostaglandin dehydrogenase. C.B. E. sphingomyelin. glycerol and choline. a phosphorylcholine group. IDL D. a ceramide group. B. C. E. Ans: D 35. D. C. G-ganglioside. sphingosine and glucose. D. Loss of hexosaminidase A activity results in accumulation of A. Which of the following serum lipoproteins possesses the highest concentration of protein (mg protein/g lipoprotein)? A. galactocerebroside. B. C. E. D. The principal apoprotein in LDL is: A. apo B-48. carbon dioxide. represent a type of co-translational modification of the protein. lecithin cholesterol acyltransferase. Ans: C 41. cholic acid conjugation. phosphatidylcholine. Cholesterol is metabolized in the mammalian body primarily by conversion to A. B. apo E. bile acids. Ans: B 38. are regulated by the level of dietary cholesterol. serum albumin. lipoprotein lipase. Ans: B 39. Transfer of cholesterol from membranes to HDL requires A. Ans: A . fatty acids. partial hydrolysis. apo CII. C. mevalonic acid. phosphatidylserine. B. control the rate of synthesis of cholesterol. C. Triglycerides. D. are induced by reabsorbed bile acids. E. C. None of the above. apo AI. phosphatidylethanolamine. Changes in the extent of phosphorylation of 3-hydroxy-3-methyl glutaryl-CoA reductase A. E. B. apo B-100.37. D. CDP-diglyceride is an intermediate in the de novo synthesis of A. E. B. C. Ans: C 40. vitamins D. B. D. D. C. palmitoyl-CoA. B. Ans: D . D. Ans: E 44. all the following are required EXCEPT A. Ethanolamine can exchange reversibly with the serine of phosphatidyl serine. in the form of phosphatidyl ethanolamine. C. The carbons of ethanolamine cannot be derived from glucose but may be derived from fatty acids.42. B. Ans: B 43. arachidonic acid of the cytosol serves as the primary precursor. D. choline. all tissues have the capacity to synthesize all of the prostaglandins. NADPH. E. Ans: B 45. Ethanolamine can be produced from serine in the form of phosphatidyl serine. PG synthase uses 2 molecules of oxygen to generate the endoperoxide PGG 2. C. B. chylomicrons are synthesized in the liver. In the synthesis of prostaglandins and thromboxanes A. E. D. For the formation of phosphatidyl ethanolamine. CDP-diglyceride. E. ethanolamine needs to be activated by ATP and CTP. C. chylomicrons transport dietary lipids. L-serine. All the following statements regarding ethanolamine are correct EXCEPT A. Ethanolamine. B. In complete biosynthesis of sphingomyelin. PGE2 synthesis would be inhibited by aspirin but thromboxane synthesis would not be affected. E. can be converted to phosphatidyl choline. Which of the following statements about chylomicrons is FALSE? A. chylomicrons have a very high ratio of lipid to protein. D. Lipoprotein lipase catalyzes the hydrolysis of lipid from the chylomicrons. chylomicron remnants are internalized by the liver. PGH2 is the precursor of PGE2 but PGI2 is the precursor of TXA2. Lipoprotein lipase degrades chylomicron triglyceride. cholesterol D. C. lanosterol . acetyl CoA and acetoacetyl CoA which is reversible. Malonyl CoA C. The liver removes the final component of chylomicron metabolism from the circulation. B. In the biosynthesis of cholesterol from Acetoacetyl CoA and Acetyl CoA. B.46. E. palmitoyl-CoA. monoglycerides. All of the following statements about chylomicron metabolism are true EXCEPT which one? A. all of the following metabolites are intermediates. chylomicrons donate apoprotein B to HDL. triglycerides. The acyl donor for cholesterol ester formation in blood is A. desmosterol C. C. C. Ans: A 49. During cholesterol biosynthesis the production of HMG CoA involves a condensation reaction of A. 7-dehydrocholesterol B. Ans: C 50. Farnesyl pyrophosphate Ans: B 48. Mevalonate E. B. The end product of chylomicron metabolism in the circulation is called a remnant particle. D. acyl carrier protein. acetyl CoA and acetoacetyl CoA which is irreversible. E. Ans: A 47. D. EXCEPT: A. Another lipoprotein donates apoprotein C to chylomicrons. acetyl CoA and malonyl CoA which is reversible. phosphatidylcholine. Dimethylallyl pyrophosphate B. The first sterol synthesized metabolically in man from acetate is A. Isopentenyl pyrophosphate D. D. acetyl CoA and malonyl CoA which is irreversible. B. C. Lipoprotein lipase A. oleoyl Co A. Ans: D 55. converts cholesteryl esters to free cholesterol in high-density lipoproteins. D. palmitoyl Co A.E. E. malonyl Co A. C. D. B. Phosphatidic acid may be the direct or indirect precursor of each of the following lipids EXCEPT A. non-esterified fatty acids to the adipose tissues. E. arachidonyl Co A. B. phosphatidylcholine B. Triacylglycerol E. Ans: D 54. Very low density serum lipoproteins (VLDL) transport A. triacylglycerol from the liver to the adipose tissues. non-esterified fatty acids to the liver. hydrolyzes triacylglycerols in lipoproteins such as chylomicrons and VLDL. cholesterol from the intestine to the liver. medium chain non-esterified fatty acids via the lymphatic system. D. VLDL . C. squalene Ans: D 51. Select the lipid fraction in blood which is most rapidly cleared? A. Ans: B 53. Glucocerebroside Ans: E 52. phosphatidylserine D. is found in lysosomes. The first step in the biosynthesis of sphingosine is the reaction between serine and A. E. phosphatidylglycerol C. hydrolyzes phosphatidylcholine (lecithin) to lysophosphatidyl choline (lysolecithin). hydrolyzes triacylglycerols in the lumen of the intestine. stearoyl Co A. reduction of a 3-keto group in ring A by an enzyme which requires NADPH as cofactor. D. D. LDL and HDL. The lipoproteins made de novo in the intestine or liver and secreted into the bloodstream are A. E. VLDL. Endocytotic blebs B. IDL and HDL. opening of an epoxide ring when a squalene derivative is cyclized to a sterol precursor of cholesterol. sphingomyelin and PAPS. direct hydroxylation of ring A by an enzyme which requires NADPH and molecular oxygen as cofactors. IDL and LDL. epimerization of a 3-alpha hydroxyl group. B. C. E. E. HDL chylomicrons LDL All are cleared at approximately same rate. Sulfatides are synthesized in a reaction between A. galactocerebroside and H2SO4. chylomicrons. Internalization of the LDL receptor occurs in specialized regions of membrane known as: A. Gap junctions E. E. galactocerebroside and PAPS. B. VLDL. ceramide and S-adenosylmethionine (SAM). Plasma membrane patches Ans: C 58. . VLDL and HDL. hydration of a 2:3 double bond in ring A. The 3-beta-hydroxyl group of cholesterol originates by A.B. Ans: C 57. chylomicrons. Ans: C 56. B. Ans: D 59. D. Coated pits D. chylomicrons. ceramide and phosphoadenosine phosphosulfate (PAPS). Microvilli C. LDL and HDL. D. C. C. C. E. Ans: C 63. a lipid substance isolated from nerve tissue must contain in its structure A. sphingosine and ethanolamine. E. D. an N-acyl fatty acid derivative of sphingosine plus a hexose. the 17-hydroxylation of pregnenolone to 17-alpha-hydroxypregnenolone. long chain fatty acid and sphingosine. cholesterol esterase conversion of cholesterol ester to free cholesterol. a 9 carbon 3-deoxy-5-amino sugar called neuraminic acid. Which of the following reactions is inhibited by aspirin? A. a polyunsaturated fatty acid esterified to cholesterol . N-acetylneuraminic acid (NANA). a fatty acyl CoA B. C.14-dihydro-15-keto-PGE2 E. Ans: B 61. ganglioside B. D. a hexose.14-dihydro-15-keto-PGE2 Ans: B 62. 15-keto-PGE2 => 13. phosphatidylcholine => arachidonic acid + 1-acylphosphatidyl choline. PGH2 => PGI2 D. The committed step in steroid biosynthesis from cholesterol is A. sphingosine Ans: A 64. C. lecithin C. Which of the following compounds contain an N-acyl fatty acid? A. To be defined as a ganglioside. PGE2 => 13. a hexose. sphingosine and phosphatidylcholine. Which of the substances below is released from lipids of the plasma membrane and provides the precursor of prostaglandins. a fatty acid and sphingosine. NANA. B. Arachidonic acid => PGH2 C. thromboxanes and leukotrienes? A. N-acetylgalactosamine.Ans: E 60. leukotriene D. B. conversion of cholesterol to pregnenolone. a hexose. plasmalogen E. None of the above. N-acetylneuraminic acid (NANA). B. the P450 dependent 21-hydroxylation of progesterone. a fatty acid. Apoprotein C II C. a polyunsaturated fatty acid E. stimulate protein synthesis at the transcriptional level. and arachidonic acid. B. Apoprotein A-I Ans: D 68. thromboxanes. Of the apoproteins listed below. cholesterol. leukotrienes. Apoprotein B-100 E. D. prostaglandins.C. C. a saturated fatty acid Ans: D 65. leukotrienes. E. Ans: E 67. chylomicrons B. Apoprotein B-48 D. and leukotrienes but not arachidonic acid. a diacyl glycerol D. are degraded primarily by the liver. prostaglandins and thromboxanes. D. B. prostaglandins. Ans: C 66. and arachidonic acid. lactose. Apoprotein D B. C. histidine. which one is recognized by the LDL receptor? A. Prostaglandins A. may be rapidly inactivated at their site of production by a specific prostaglandin dehydrogenase. cerebroside. Which lipoprotein contains the lowest ratio of lipid to protein? A. ganglioside. but not leukotrienes and arachidonic acid. Glucocorticoid inhibition of phospholipase A2 has the effect of inhibiting the synthesis of A. all stimulate the production of cAMP. but not thromboxanes. HDL . generally are secreted by one tissue and exert their effects on a different target tissue. thromboxanes. Ans: D 69. prostaglandins. C. E. D. B. Tay-Sachs disease is the result of an inborn error of metabolism of A. cholesterol esterase. D. CDP-choline and 1. acetyl-CoA and malonyl-CoA B. B. cholesteryl oleate. APO AI B. gangliosides. ceramide and CDP-choline D. ceramide. APO CII D. LDL E. phosphatidylcholine. Ans: B 71. palmitoyl-CoA and acetyl-CoA Ans: D 72. E. lecithin-cholesterol acyl transferase. A general enzyme for the esterification of intracellular cholesterol is A. C. Ans: C 73. palmitoyl-CoA and serine E. CoA transferase. E. Sphingosine is a product of the condensation of A.2-diacylglycerol C. APO E Ans: A . B. IDL D. none of the other Answers is correct. VLDL Ans: B 70. APO B-100 C. acyl-CoA-cholesterol acyl transferase. Which of the following apoproteins serves as a cofactor (activator) for lecithin: cholesterol acyltransferase (LCAT)? A. C.C. The substrate for the synthesis of prostaglandins and leukotrienes is released from endogenous A. D. plasmalogen. . phosphoethanolamine. monoacylglycerol. D. C. inositol 1. C. It is involved in prenylation of proteins where the first step is transfer of the farnesyl group to the protein and loss of the phosphates. phosphocholine. EXCEPT A. Ans: D 76. C. fatty acid. An important function of high density lipoproteins (HDL) is the A. transport of triacylglycerols from liver to adipose. B. at least partly. The action of a phospholipase C on a phospholipid substrate may yield A. B. It is a product of Squalene. Cerebrosides can be formed by the contribution of all of the following. transport of bile lipids from liver to gall bladder. cleaves a fatty acid from the 1 position of phosphatidic acid. C. glycerol. glycerol. choline. be inhibited by Lovastatin. long chain fatty acid. D. Ans: C 75. It is made during the synthesis of cholesterol. E. E. B. glucose.74. catalyzes the formation of a phosphodiester. Ans: B 78. deposition of cholesteryl esters in atherosclerotic lesions. E. diacylglycerol. acquisition of cholesterol from tissues and other lipoproteins. The enzyme phosphatidate phosphatase A. fatty acids. B. palmitic acid. Ans: B 77. serine. Which statement is false concerning farnesyl pyrophosphate? A.5-trisphosphate. phosphoceramide. B. transport of glycerophospholipids from liver to intestine. It is an eventual product of activated isoprenes.4. cleaves phosphate from the 3 position of phosphatidic acid. D. C. E. D. Its formation would. D. cleaves phosphate from the 2 position of phosphatidic acid. cleaves a fatty acid from the 2 position of phosphatidic acid. C. cholesterol. dipalmitoyl phosphatidyl choline. dipalmitoleoyl phosphatidylcholine D. farnesyl pyrophosphate. B. E. desmosterol. Premature infants may exhibit the respiratory distress syndrome due to inadequate secretion of A. Ans: E . Ans: B 83. E. decreased LDL endocytosis. a potent smooth muscle contractor (vasoconstrictor). acetyl CoA --> hydroxymethylglutaryl CoA --> mevalonate --> lanosterol C. D. C. increased cholesterol synthesis.Ans: A 79. Which of the following metabolic pathways is CORRECT? A. increased serum cholesterol. a potent platelet aggregator. Ans: E 81. C. E. geranyl pyrophosphate. D. lanosterol --> squalene --> mevalonate --> cholesterol B. cholesterol. increased 3-hydroxy-3-methyl glutaryl-CoA reductase activity. dioleoyl phosphatidyl inositol. Squalene is the immediate precursor of A. C. decreased serum LDL. Prostacyclin (PGI) is A. the long sought slow-reacting substance of anaphylaxis (SRSA). mevalonate --> hydroxymethylglutaryl CoA --> squalene --> cholesterol D. formed from arachidonic acid by the action of lipoxygenase. B. Ans: A 82. a potent smooth muscle relaxer (vasodilator). An LDL receptor deficiency could cause all of the following to occur EXCEPT A. E. B. D. mevalonate --> lanosterol --> squalene --> cholesterol Ans: B 80. lanosterol. sphingomyelin B. phosphatidylcholine is made from CDP-choline and diacylglycerol E. E. only one fatty acid residue. Ans: B 87. an ethanolamine residue. D. C. B. polypeptide residue. C. which of the following statements is false? A. C. phosphatidylserine is made from CDP-serine and diacylglycerol D. phosphatidylcholine can also be made from phosphatidylethanolamine via three methyltransferase reactions Ans: C . sphingomyelinase. aryl sulfatase. Materials that accumulate in the brain and other tissues of patients afflicted with the various lipidoses all contain as a common structural feature A. hexosaminidase. an N-linked fatty acid residue. E. An accumulation of gangliosides in brain tissue most likely arises from a deficiency of lysosomal A. B. nitrogen and sulfur. Ans: C 85. As regards glycerophospholipid biosynthesis in mammals. ceramide structure.84. E. phosphatidylinositol is made from CDP-diacylglycerol and inositol C. D. phospholipase A2. acyltransferase. phosphatidylethanolamine is made from CDP-ethanolamine and diacylglycerol B. phosphatidic acid structure. Ans: C 86. B. sialic acid structure. phosphorus. a residue of glycerol. triglyceride structure. A molecule of sphingomyelin is similar to a molecule of lysolecithin in that both contain A. D. B. pyrophosphorylated intermediates are used. HMG-CoA is a precursor of all of the following EXCEPT A. D. The enzymes responsible for the degradation of sphingolipids are localized in which subcellular structure? A. Statements in accord with the behavior of the membrane receptors for serum low density lipoproteins (LDL) include all of the following EXCEPT A. the receptors reappear in the plasma membrane. biotin. three carbons are lost as propionyl-CoA. C. E. C. they are inserted into the plasma membrane at random sites. Ans: A 91. D. the receptor for LDL will not bind the high density lipoprotein (HDL). B. In the synthesis of cholesterol from lanosterol A. Peroxisomes B. Rough endoplasmic reticulum Ans: C 92. B. once internalized. Cholesterol is a source of which of the following substances of biological importance? A. Mitochondria C. acetoacetate. cholesterol. C. isoprene units and carotene D. ketone bodies. they require LDL to be present for recycling. bile salts and carotene C. they migrate laterally in the plane of the membrane. Ans: D 90. the side chain becomes saturated.88. E. an anaerobic environment is required. the number of rings decreases from five to four. Lysosomes D. Smooth endoplasmic reticulum E. steroid hormones and taurine B. isopentenyl pyrophosphate. bile salts and pregnenolone Ans: D 89. D. . E. phosphatidic acid B. pancreatic lipase. cholesterol Ans: A 96. fatty aldehydes D. phosphatidylcholine (lecithin) C. C. carnitine. B. lipoprotein lipase. Diphosphatidylglycerol (cardiolipin) B. A ganglioside . AMP. phosphatidylserine D. Apoprotein CII activates A. phosphatidylinositol E. Ans: A 94. E. Sphingomyelin E. D. CoA. In phospholipid synthesis. either phosphatidic acid or phosphoryl head group is activated for transfer by conjugation to A. Which of the following substances is an intermediate in the synthesis of both triacylglycerols and diacylphosphoglycerides? A. B.Ans: D 93. phospholipase A2. Ans: A 95. pyridoxal phosphate. hormone sensitive lipase. CDP-choline C. C. D. lipoxygenase. CMP. E. Which of the following accumulates in tissues of patients with Niemann-Pick disease? A. isopentenyl pyrophosphate. Acetyl CoA.Ans: D 97. C. from lanosterol. B. prostaglandins and prostacyclin are characterized by long half-lives. by a phosphorylation reaction. acetone. C. releasing the saturated fatty acids from lecithin. protection of the central nervous system from neurodegenerative diseases. Ans: B 101. an intermediate is A. D. internalization of cholesterol by endocrine cells for hormone synthesis. Ans: D 100. Ans: C 98. C. B. E. Ans: A 99. D. arresting inflammation. degrading phosphatidic acid. by an oxidation. delivery of cholesterol to liver for bile lipid synthesis. B. . E. acetoacetyl CoA. Omega-6 fatty acids are essential for the production of eicosanoids. D. Phospholipase A2 plays a biologically significant role in A. In the biosynthesis of cholesterol from mevalonic acid. B. B. uptake of triacylglycerol by adipose for storage. D. D. Squalene is formed A. redistribution of apoprotein E among lipoproteins. by a reductive condensation reaction. C. releasing arachidonic acid for the synthesis of prostaglandins. beta-hydroxy-beta-methylglutaryl CoA (HMG CoA). degrading lysolecithin. Leukotrienes are derived from arachidonic acid by lipoxygenase. E. A principal function of the apo-E receptor (remnant receptor) is the A. All of the following regarding eicosanoids are true except: A. prostaglandins and thromboxanes are derived from arachidonic by cyclooxygenase. C. VLDL and LDL E. B. in the plasma. LDL and VLDL D. glucocerebroside. D. hormone sensitive lipase C. E. sphingosine. the conversion of phosphatidylethanolamine to phosphatidylserine. the uptake of choline into cells. pancreatic lipase D. D. B. B. covalently linked monosaccharide units. terminal sialic acid. E. galactocerebroside. LDL and HDL Ans: D 104. C. phospholipase A2 E. Ans: B 106. E. Important in prostaglandin synthesis A. phosphatidylethanolamine. lipoprotein lipase B. In the absence of dietary fat intake. ganglioside. chylomicra and HDL B. A ceramide residue is found in all of the following EXCEPT A. ceramide. the characteristic feature of a ganglioside is A. RESPECTIVELY. the action of phospholipases. C. Ans: E 103. A.Ans: C 102. D. N-acyl unsaturated fatty acids. the intra membrane transport of phospholipids. colipase Ans: D 105. . sphingomyelin. Compared to other lipids. Phospholipid exchange proteins are known to be involved in A. C. identify the lipoproteins which are the major carriers of triacylglycerol and of cholesterol esters. VLDL and HDL C. the intermembrane transport of phospholipids. 4 carbon atoms. E. C. As regards prostacyclins. None of the above. They are products of lipoxygenase. Mevalonate contains A. which of the following statements is/are true? A. phosphatase and kinase E. D. synthase and lyase Ans: D 109. desaturase and reductase C. B. D. They stimulate platelet aggregation. 15 carbon atoms. D. acyltransferase and phospholipase B. Aromatization of the A-ring C. They are made in endothelial cells. Ans: D 108. are involved in the transport and delivery of cholesteryl esters. are substrates for hormone sensitive lipase. 27 carbon atoms. by uncontrolled self-replication are the cause of hypercholesterolemia. Hydroxylation at C-3 Ans: E 110. B. C. LDL A. Incorporation of a methyl group at C-19 B. lipase and acyl-CoA synthetase D. C. Ans: D 111. Cleavage of the side chain at C-17 E. Attachment of a hydroxyl group to the C ring D. They are made in platelets. The interconversion between phosphatidate and diacylglycerol requires which of the following pairs of enzymes activities? A. 6 carbon atoms.Ans: B 107. Which of the following chemical changes is required for the conversion of squalene to cholesterol? A. . provide the major means of triacylglycerol transport. B. increased synthesis of glycosphingolipids. Which of the following compounds may be a constituent of a phospholipid and serves as the precursor of leukotrienes? A. arachidonic acid C. glycerol. acetic acid B. choline. C. LDL E. C. inositol D. are unique in containing no lipids. HDL C. . chylomicrons D. sphingosine. phosphate. Lipid storage diseases such as Niemann-Pick's. E. Ans: B 112. High density lipoprotein (HDL) contains more than 20% by weight of lipid. inadequate lysosomal hydrolase activity. Ans: C 115. E. inadequate synthesis of ceramide. oleic acid E. polyacetylphosphatidic aci Ans: B 114. EXCEPT A. defects of glycogen synthesis. Which one of the following statements concerning lipoprotein metabolism is CORRECT? A. palmitic acid. B. D. VLDL B.E. The largest and lowest density lipoproteins are the A. B. Tay-Sachs' and Gaucher's involve A. Ans: B 116. Lecithin consists of all of the following components. increased amounts of glycosphingolipid in the diet. IDL Ans: C 113. D. D. E. Ans: A 117. intermediate density lipoprotein. C. low density lipoprotein. Low density lipoprotein (LDL) has a half life of several hours. Very low density lipoprotein (VLDL) contains less than 20% of triglyceride.3-dimethylallyl pyrophosphate. HMG-CoA synthase catalyzes the reaction between two molecules of acetyl-CoA. Acetyl CoA and malonyl CoA which is reversible. Ans: B 120. Ans: C 118. In the biosynthesis of cholesterol. None of the above. D. Acetyl CoA and Acetoacetyl CoA which is irreversible. E. HMG-CoA reductase is activated by cholesterol. B. D. polymerization of a 5-carbon isoprene unit gives rise to a 30-carbon hydrocarbon called A. C. high density lipoprotein. chylomicron. B. HMG-CoA. very low density lipoprotein. C. D. Ans: E 119. cholesterol synthesis occurs in the mitochondria of cells. Synthesis of chylomicrons is inhibited by ketone bodies. C. C. Squalene is formed by reduction of lanosterol. 3. E. Very low density lipoprotein synthesis is inhibited by high carbohydrate diets.B. Acetyl CoA and malonyl CoA which is irreversible. Ans: D . B. none of the above. The second step in the first stage of cholesterol biosynthesis leading to production of HMG CoA involves a condensation reaction of: A. D. B. Which of the following statements is true concerning cholesterol metabolism? A. E. squalene. E. The plasma lipoprotein most likely to transport triacylglycerols from the liver to the heart is the A. Acetyl CoA and Acetoacetyl CoA which is reversible. Mevalonate is produced by the reduction of HMG-CoA. geranyl pyrophosphate. choline. C. It is an integral part of membranes. D. 3 and 4 Ans: B 122. fatty acid. Only 2. Ans: A 124. E. They enter cells via a specific membrane receptor. B. 2 and 4 D. LDL-particles are involved in all of the following EXCEPT which one? A. E. D. Which of the following molecules are phospholipids? 1. B. Cerebroside A. 3 and 4 E. D. C. Only 1 and 3 C. acetoacetate. Cephalin 4. cholesterol. Cardiolipin 2. Ceramide 3. free diacylglycerol (diglyceride). All the statements concerning phosphatidyl choline (lecithin) are TRUE EXCEPT A. It possesses three fatty acyl groups in its structure. Ans: A . Sphingomyelin consists of all of the following components. It can be synthesized using a CDP-derivative as an intermediate. CTP is an important nucleotide in the biosynthesis of A. triacylglycerol (triglyceride). They carry TG's. sphingosine. EXCEPT A. B. phosphatidylcholine. C. E. It can be synthesized using S-adenosyl methionine as an intermediate. 1. They are stabilized by the protein Apo-A. Ans: B 123. B. E. glycerol. Only 1. Only 1 B. phosphate. 2. Ans: A 125. cholesterol and phospholipids. It is found in most lipoproteins. They are present in high amounts in the plasma of patients with familiar hypercholesterolemia. They are degraded intracellularly by lysosomal enzymes. C. D.121. D. D. 11beta-hydroxylase. The rate limiting step in the synthesis of bile acids from cholesterol is catalyzed by A. coprostanol E. where circulating triacylglycerols are enzymatically digested. farnesyl pyrophosphate D. exchange of ethanolamine of phosphatidylethanolamine with serine. blood. cholyl-CoA B. B. acetoacetyl-CoA + acetyl-CoA --> HMG-CoA + CoA in the mitochondria. Ans: C 128. C. acetoacetyl-CoA ---> beta-hydroxybutyryl-CoA in the cytosol. 2 acetyl-CoA --> acetoacetyl-CoA in the mitochondria. where stored triacylglycerols are mobilized. reaction of diglyceride with CDP-serine. adipose tissue. side-chain cleavage enzyme. B. acetoacetyl-CoA + carnitine --> acetoacetyl-carnitine + CoA at the inner mitochondrial membrane. C. phosphatidylserine is formed A. B. Ans: E 130. D. Which of the following is a precursor of squalene and is derived from geranyl pyrophosphate? A. where dietary triacylglycerols are absorbed. HMG-CoA + 2 NADPH --> mevalonic acid + 2 NADP + CoA in the endoplasmic reticulum.126. C. 7alpha-hydroxylase. 21beta-hydroxylase. small intestine. Ans: A 129. from reaction of serine with CDP-diacylglycerol. liver. D. Ans: B 127. where endogenous triacylglycerols are synthesized. lanosterol Ans: C . squalene synthase. E. In mammals. C. The formation of very low density lipoproteins takes place in the A. B. mevalonic acid C. E. The first reaction which is unique to the isoprenoid biosynthetic pathway is A. carboxylation of phosphatidylethanolamine. lipoxygenase B. Sphingosine. D. dihydroxy alcohol named A. apo-A B. apo-D D. ceramide. Concerning the biosynthesis of the sphingolipids. C. Ans: C 135. acyl-CoA dehydrogenase. They contain one molecule of sphingosine. 15-hydroxyprostaglandin dehydrogenase. D. They are found only in neural tissues. D. apo-C C. Ans: B 134. All of the following statements about gangliosides are TRUE except A. E. cerebroside. E. They contain sugars in beta linkage. E. one of the precursors of sphingomyelin is an unsaturated monoamino. C. Sphingomyelin B. B. cyclooxygenase. prostaglandin endoperoxidase. They contain one or more sialic acid molecules. sphinganine. C. apo-B Ans: D 133. Which of the following compounds is a glycolipid? A. ganglioside. prostaglandin E2 is inactivated in a reaction catalyzed by A. phosphatidyl choline C.131. Ans: A 132. cholesterol D. B. Ganglioside . They contain a fatty acid molecule. The release of nascent chylomicrons and/or VLDL requires which apoprotein? A. Which of the following statements about plasma lipoproteins is INCORRECT? A. phosphatidate. Ceramide B.E. phosphatidylcholine. A high carbohydrate diet leads to an elevation of VLDL. D. Sphingomyelin C. Cytidine triphosphate (CTP) would be utilized in the synthesis of all of the following EXCEPT A. The liver responds to an increase in the flux of free fatty acids with the synthesis of more and larger HDL. Apo B-100 is the only apolipoprotein associated with LDL. phosphatidylglycerol. Ans: C 139. C. C. The rate controlling step in cholesterol synthesis is catalyzed by A. D. phosphatidylinositol. B. Sphinganine D. C. Cerebrosides Ans: B 137. E. E. The triacylglycerol core of chylomicrons is derived primarily from dietary lipids. Which of the following is synthesized by action of squalene cyclooxygenase upon squalene? . mevalonate kinase. B. phosphatidyl serine Ans: D 136. phosphatidylethanolamine. B. D. Ans: A 138. isopentenyl diphosphate isomerase. E. VLDL is the precursor of LDL in the blood. Ans: E 140. Which has a head group containing phosphorus? A. hydroxymethylglutaryl coenzyme A reductase. methyl sterol oxidase. squalene monooxygenase. C. sphingomyelin B. long-chain fatty acid in amide linkage. farnesyl pyrophosphate D. Which of the following lipids is most closely thought of as a lung surfactant? A. D. LPL activity is highest in adipose tissue in the fasted state. It only attacks lipoproteins which possess apoprotein A. D. phosphatidylcholine oleate sphingomyelin glycocholate triacylglycerol Ans: E 144. D. sugar. B. sphingosine. E. E. cholyl-CoA B. E. phosphate. C. cholesterol linoleate Ans: C 143. Ans: C 142. C. mevalonic acid C. Cerebrosides contain all of the following residues EXCEPT which one? A. dipalmitoylphosphatidylcholine D. LPL activity is highest in skeletal muscle in the fed state. Which one of the following statements about lipoprotein lipase (LPL) is true? A. lanosterol Ans: E 141. ceramide. The products of its action are glycerol and free fatty acids. glycerol tristearate E. coprostanol E.A. Ans: E . B. cardiolipin C. All of the following compounds are amphipathic EXCEPT which one? A. B. It is responsible for converting chylomicrons to IDL. C. E. B. B. C. CTP. decreased esterification of cholesterol. HDL. D. decreased lysosomal enzyme activity. remnant particle. HDL. Diacylglycerol. ATP. phosphorylcholine. D. B. D. E. UDP-choline. acquisition of apoprotein E from plasma. Ans: D 147. Ans: D 146. C. increased formation of modified low density lipoproteins. LDL. nascent HDL. E. C. The primary metabolic defect in the disease familial hypercholesterolemia is A. increased hormone-sensitive lipid mobilization. D. decreased receptor-mediated endocytosis. LDL is derived from A. Ans: D . E. one critical step is the A. cleavage of apoprotein B-100 to apoprotein B-48. Ans: C 148. chylomicrons. it becomes a A. Ans: E 149. None of the other answers is correct. increased hydrolysis of triacylglycerol. B. As the chylomicron is acted on by lipoprotein lipase.145. B. VLDL and IDL. C. Each of the following metabolites is a substrate directly involved in the biosynthesis of phosphatidyl choline from choline EXCEPT A. In the transformation of very low density lipoprotein to low density lipoprotein. D. VLDL. altered prostaglandin synthesis. binding to one of the scavenger receptors. catalyzes a reaction between oleoyl-CoA and cholesterol Ans: A . Lecithin-cholesterol acyl transferase (LCAT) A.150. B. is dependent on presence of heparin. D. E. must be bound to the capillary endothelium before it hydrolyzes cholesterol esters. catalyzes formation of cholesterol esters in the Golgi during VLDL synthesis. C. catalyzes formation of cholesterol ester from free cholesterol and phosphatidylcholine. it lowers calcium and phosphorus levels in plasma upon prolonged administration B. In general. decreases TRH secretion by the hypothalamus E. androgen activity. C. circulates bound to thyroglobulin C. secretion is increased by thyrocalcitonin Ans: D 4. the steroid hormones act by affecting the rate of protein synthesis. In general. its secretion is inhibited by high levels of plasma calcium C. mineralocorticoid activity. B. C. E. Ans: D 3. steroid hormones take a rather long time (1-8 hours) to produce an effect. Which one of the following statements BEST describes the action of the parathyroid hormone? A. it lowers serum calcium levels and raises serum phosphate levels D. glucocorticoid activity.Chapter 23 Biochemistry of Hormones Multiple Choice 1. steroid hormones are lipid-soluble. Thyroxine A. therefore Can readily traverse the cell membranes. B. steroid hormones combine with a cytoplasmic receptors and stimulate the production of cAMP. Cortisol has primarily A. estrogen activity. it stimulates reabsorption of phosphate from the kidney Ans: B . All of the following statements regarding the mechanism of action of the steroid hormones are true EXCEPT which one? A. it causes (or enhances) precipitation of calcium salts in bone E. D. biosynthesis and secretion by the thyroid is directly stimulated by thyrotropin releasing hormone (TRH). D. None of the above is true. D. Ans: C 2. decreases tissue oxygen consumption B. D. cyclic AMP and the cyclic AMP-dependent protein kinase. cortisol. Ans: C 8. the receptor. D. cyclic AMP and the substrates to be phosphorylated. which one. B. the receptor. E. the receptor and the substrates to be phosphorylated. Adrenocorticotropic Hormone (ACTH) is a steroid hormone. if any. Hormones do not enter the blood but act locally on surrounding cells. is true? A. Ans: B 7. Initially. Of the following statements concerning human hormones. the cyclic AMP-dependent protein kinase and the substrates to be phosphorylated. the ability to bind steroid hormones. D. B. Specificity in the action of a peptide hormone is determined at the level of A. 17-hydroxyprogesterone. Ans: E 6. Pregnanediol is a metabolite of A. none of these. progesterone. their location in the cytosol. The insulin-receptor has in common with other growth-factor receptors such as epidermal growth factor A. Excess/abnormal thyroid hormone produced by a thyroid carcinoma is termed ectopic production. androstenedione. E. D. the ability to phosphorylate tyrosine residues on certain proteins. None of the above.5. E. the presence of a bound GTP. B. C. Ans: A . all hormones are synthesized in the cell as a prohormone. C. E. estradiol. C. B. C. the ability to phosphorylate serine residues on certain proteins. produces carbon dioxide. E. NADPH and oxygen are required. The conversion of androgens to estrogens involves the aromatization of the "A" ring and the loss of two methyl groups. The catabolism and excretion of steroid hormones A. C. hypercalcemia and hypophosphatemia . E. the 3-0-methylation of the catechol nucleus by catechol-0-methyl transferase. C. Ans: D 11. binds to plasma membrane receptors and activates adenylate or guanylate cyclase D. B. the decarboxylation of dihydroxyphenylalanine by DOPA decarboxylase. occurs primarily as the bile salts. synthesis requires iodination of a cellular protein in the thyroid Ans: E 13. Testosterone can be a precursor of estrogens. hypocalcemia and hypophosphatemia C. is the only hormone synthesized by the thyroid gland C. D. usually involves transmethylation reactions. Thyroxine A. the hydroxylation of L-tyrosine by tyrosine hydroxylase. The placenta can convert DHEA-sulfate into estrogens. D. Ans: D 12. Which of the following occurs subsequent to administration of parathyroid hormone? A. C. In normal animals and an. is synthesized by iodination of free tyrosine molecules in the thyroid gland B. the rate-limiting step in the biosynthesis of the catecholamine neurotransmitters dopamine and norepinephrine is A. the action of monoamine oxidase on the beta-phenethylamine nucleus. hypercalcemia and hyperphosphatemia B.9. may involve conjugation of a metabolite with sulfate or glucuronate. is transported to its target tissue free in solution in the blood E. E. Ans: C 10. B. B. Androgens can be converted to estrogens in adipose tissue. requires reduction and cleavage of the steroid nucleus. D. Which one of the following statements concerning the formation of estrogens is FALSE? A. the transport of L-tyrosine across the blood brain barrier. thyroglobulin. Ans: E 15. adenylate cyclase. C. the receptor. B. Specificity in the action of a peptide hormone is determined at the level of A. none of the above is correct Ans: C 14. C. A and C only. the receptor and the substrates to be phosphorylated. triiodothyronine. In addition to activating the intrinsic tyrosine kinase of the receptor. B. None of the above. insulin binding also activates a phospholipase c and induces production of the phosphatidylinositol second messengers. As regards the insulin receptor. The signaling mechanism whereby glucagon results in an increased breakdown of triacylglycerol in adipose tissue involves all of the following EXCEPT A. E. E. B. thyroxine. a transmembrane receptor. E. E. if any. diiodotyrosine. Ans: C 17. the receptor. which of the following statements. Which vitamin is a secosteroid and acts through a steroid receptor? . Ans: E 16. B. none of these.D. The active receptor is made up of 1 alpha chain and 1 beta chain. phospholipase A2. a trimeric Gs protein. D. Ans: C 18. protein kinase A. hypocalcemia and hyperphosphatemia E. The alpha chain spans the membrane while the beta chain binds the insulin molecule. cyclic AMP and the cyclic AMP-dependent protein kinase. is/are true? A. C. the cyclic AMP-dependent protein kinase and the substrates to be phosphorylated. D. D. c. D. The thyroid hormone found in highest concentration in blood is A. monoiodotyrosine. cyclic AMP and the substrates to be phosphorylated. Cyclic AMP phosphodiesterase Ans: B 20. dopamine cannot pass the blood brain barrier and is provided to patients with Parkinson's disease in the form of DOPA B. Catechol-o-methyl transferase C. B. have specific metabolic effects C. B. E. act on one or more target tissues E. Dopamine-beta-hydroxylase D. steroids increase RNA polymerase II activity. steroids increase the half-life of specific proteins. pyridoxal phosphate and SAM as cofactors C. synthesis of epinephrine and norepinephrine takes place in the adrenal medulla D. steroids increase the half-life of the mRNAs that encode specific proteins.A. tyrosinase is one of the enzymes involved in catecholamine biosynthesis . steroids increase the rate of synthesis of specific mRNAs. C. The following are TRUE statements concerning catecholamines EXCEPT A. D. Phenylethanol amine-N-methyl transferase B. Which of the following enzymes is involved in the metabolism (breakdown) of epinephrine? A. Which one of the following statements does not describe a characteristic of hormones? A. bind either to cell surface or to intracellular receptors Ans: C 22. synthesized in endocrine glands B. Aromatic decarboxylase E. D. C. Ans: C 21. Which of the following best describes the mechanism by which steroid hormones increase the relative abundance of specific proteins? A. are considered to be secondary messengers D. steroids increase the translatability of specific mRNAs. the synthesis of epinephrine requires tetrahydrobiopterin. Vitamin A Vitamin C vitamin D Vitamin E Vitamin K Ans: C 19. E. It functions as an anchor for the receptor B. It has some intrinsic catalytic kinase activity. Thyroid hormone is produced in the thyroid gland A. histone proteins. in a process that involves the iodination of single tyrosine molecules prior to incorporation into thyroglobulin . Decreasing the production of cyclic AMP. non-histone proteins. It contains a regulatory sequence which produces a low affinity ligand binding site. Alteration of the phosphorylation of histones. Estrogen is thought be exert its metabolic effects by which one of the following? A. RNA polymerase. DNA. D. E. Ans: A 26. B.E. Ans: A 24. D. Increasing the permeability of cell membranes to molecules such as glucose and amino acids. C. Ans: C 25. E. Specificity in the action of steroid hormones is determined at the level of A. C. Reaction with a specific receptor protein which in turn affects DNA metabolism. Which of the following is/are characteristic of the transmembrane domain of a typical tyrosine kinase receptor? A. C. It controls negative feedback upon ligand binding. the nuclear membrane. A and B only. D. B. catabolism of catecholamines involves oxidative removal of the amino groups by monoamino oxidase (MAO) and methylation of OH-groups by catechol-Omethyltransferase (cOMT) Ans: D 23. stimulates osteoclasts to break down bone mineral E. LH . prolactin . pregnenolone Ans: E 29.glucocorticoid D. counteracts the effect of the active metabolite of vitamin D on the kidney . Purines E. stimulates reabsorption of phosphate by the kidney D. 17 alpha-hydroxy pregnenolone E. C and D Ans: C 27. steroids B. produces. Glycoproteins Ans: D 28. Amines D.B. stored in the follicle. and released into the blood stream after proteolysis of thyroglobulin in phagolysosomes of the thyroid cell D. lowers the concentration of free calcium ion in blood C.estrogen E. ACTH . in intestinal epithelial cells. Parathyroid hormone A.inhibin Ans: D 30. after which T4 and T3 are stored as active hormones in the colloid of the thyroid follicles C.androgen B. with a ratio of T3 to T4 of approximately 151 E. TSH . Which of the following hormone combinations is NOT regulated by a negative feedback loop? A. All of the following compounds could serve as androgen precursors EXCEPT which one? A. Examples of hormones have been found which belong to each of the following chemical families EXCEPT which one? A. FSH . cortisol B. new mRNA which codes for calcium ion transport protein B.thyroid hormone C. Peptides C. 11-desoxycortisol C. 17 alpha-hydroxy progesterone D. What is the mechanism of this inhibition? A. Ans: D 33. C. Ans: E 34. E. All of the other s are correct. C. ERb binds the ERa ligand D.Ans: D 31. Ans: A 32. stimulates the phosphodiesterase enzyme which breaks down cAMP. Which of the following statements is false? . never results in the formation of estrogens. E. Biological conversion of testosterone A. has the same effect on glycolysis in the liver as glucagon. does not occur in androgen target tissues. The estradiol receptor Erb can inhibit the activity of ERA. steroid hormone action involves specificity at the levels of both cytosolic receptor and chromatin sites. Formation of heterodimers of the two receptors E. inhibits hepatic glycolysis. decreases the concentration of fructose-2. may lead to even more active androgens being formed. B. Blockage of transport of ERa into the nucleus B. Insulin A. D. Inhibition of synthesis of ERa Ans: D 35. Which statement BEST describes the regulatory action of steroid hormones on cellular metabolic events? A. does not take place. D. B. C. leads only to the production of 17-ketosteroids. B. steroid hormones serve as signals to alter cellular metabolism in response to environmental changes. E. steroid hormones are capable of specific interactions with the genomes of their target cells. stimulates glucose transport into the liver. D. steroid hormones act as an independent regulatory system relative to cyclic nucleotide systems. Dissociation of the ligand from ERa C.6-bisphosphate in liver. cholestanone . 7-hydroxycholesterol C. In humans. C. through an intracellular receptor that binds to DNA. binds to a cytoplasmic protein receptor and is transported to the nucleus of its target cell. Which one of the following is a pro-vitamin D? A. Ans: D 36. In humans. would circulate in the blood primarily as the free hormone. Dehydroepiandrosterone E. results in the activation of certain enzymes by stimulating their phosphorylation. C. by directly activating a protein kinase. B. Ans: D 39. Testosterone Ans: A 37. B. by blocking expression from target genes. Ans: B 38. C. Aldosterone is only produced in which portion(s) of the adrenal gland? A. there exists known protein kinases that phosphorylate proteins on tyrosine. 25-hydroxycholecalciferol B. by directly binding to glucocorticoid responsive elements (GREs) near the ' end of target genes. 7-dehydrocholesterol D. The glucocorticoid hormones act A. E. B. E. results in increased glucose in the blood. Corticosterone C. In humans. is released from the adrenal cortex by ACTH. Hormones exert their effects by interacting/binding to specific receptors which may be in the cell membrane or intracellular. ergocalciferol E. at the cell surface by binding to specific membrane-bound receptors. Zona glomerulosa of the cortex B. D. there exists known protein kinases that phosphorylate proteins on methionine. there exists known protein kinases that phosphorylate proteins on serine. Phosphorylation plays an important role in many hormonal effects.A. Aldosterone D. D. Aldosterone A. E. D. the one converting cholesterol to 7-dehydrocholesterol. . E. C. acts on the distal part of the nephron. binding of the receptor to double-stranded DNA. transduction of a signal by intrinsic tyrosine phosphorylation. 18-hydroxylase. All of the following would be caused by or would be the result of increased levels of epinephrine in the circulatory system EXCEPT A. phosphorylation in liver cells of sidechains of specific serine units of certain proteins. E. Ans: B 41. C. is secreted in response to decreased plasma osmolality. B. Ans: A 44. B. Vasopressin (ADH) A. interaction of the receptor with a heterotrimeric G protein. The identification of zinc finger domains in the structure of a hormone receptor would predict A. C. D. increased breakdown of liver glycogen. E. Ans: D 43. is secreted in response to elevated blood pressure. D. production of cyclic-AMP. fat and albumin synthesis and simulates lipogenesis in adipocytes. stimulation of a phosphoprotein phosphatase. HMG-CoA reductase. acts on uterine smooth muscle. Which of the following enzymes catalyzes the rate controlling step in cortisol biosynthesis? A. activation of a protein kinase. 11-hydroxylase.Ans: C 40. Which of the following statements is false? A. D. B. migration of the receptor from vesicles to the plasma membrane. B. regulation of the receptor by protein kinase C. C. Ans: A 42. insulin is made by the pancreatic beta cells and stimulates liver glycogen. the one converting cholesterol to delta-5-pregnenolone. D. Which of the following steroids serves as the immediate precursor for the synthesis of estradiol? A. D. In the adrenal medulla. The major actions of parathyroid hormone are . DOPA decarboxylase requires pyridoxal phosphate as a cofactor. is the major regulator of sodium ion retention in the kidney in man. E. In the adrenal medulla. binds to a nuclear receptor. Testosterone C. is a 19-nor compound. Ans: E 48. D. E. Ans: B 47. C. B. is converted in peripheral tissues directly to reverse T3 (3. Pregnenolone Ans: B 46. contains 20 carbons. C. monoamine oxidase and catechol O-methyl transferase. is less potent in vivo than T4. B. Glucagon is made by the pancreatic alpha cells and stimulates liver glycogenolysis. gluconeogenesis and ketogenesis and stimulates lipolysis in adipocytes. Dehydroepiandrosterone E. decreases basal metabolic rates of most tissues. epinephrine is broken down by two enzymes. is produced primarily in the adrenal medulla. Progesterone D. D.B. E. C. Ans: C 45. The rate controlling step/enzyme in the synthesis of epinephrine by the adrenal medulla is the formation of dopamine from DOPA via DOPA decarboxylase. is the predominant thyroid hormone produced by thyroid gland.3'5' triiodothyronine). Cortisol B. Triiodothyronine (T3) A. Aldosterone A. is regulated by ACTH. all of the above E. C. initiates tyrosine kinase activity after insulin binds to the beta-subunit D. enhancement of calcium excretion by direct effect on the kidney tubules direct promotion of bone resorption with increased osteoclastic activity enhancement of renal clearance of phosphate A and C above B and C above Ans: E 49. The insulin receptor A. A & C only Ans: A 50. initially bind triiodothyronine in the cytoplasm and after undergoing a conformational change translocate to the nucleus. transports glucose into the cell after insulin binding C. B. threonine E. serine D. androsterone E. Thyroid hormone receptors A. are histone proteins localized in the chromatin of target cells. is a transmembrane protein composed of alpha and beta subunits B. cortisol B. D. Ans: B 52. B. Which of the following is a major mineralocorticoid in man? A. cysteine B. E. aldosterone D. The insulin receptor is regulated by (auto) phosphorylation of one or more _______________ residues. C. A. are enzymes that deiodinate thyroxine to triiodothyronine. vasopressin Ans: C 51. tyrosine Ans: E . are intrinsic non-histone chromosomal proteins.A. corticosterone C. D. E. have higher affinity for thyroxine than triiodothyronine. histidine C. Hypothalamic hormones which regulate the synthesis and secretion of anterior pituitary hormones include all of the following EXCEPT A. Parathyroid hormone is produced by the parathyroid glands located within the thyroid gland and calcitonin is produced by the clear cells within the thyroid gland. C. insulin-stimulated proteolysis of its receptor. Ans: B 55. A. negative cooperativity of insulin binding. a receptor that. in turn. Ans: C 56. E. D. In eukaryotic cells. C. interacts with DNA and activates transcription. C. migrates to the nuclear matrix and blocks RNA degradation. in turn. E. B.53. The main targets for Parathyroid hormone are the kidney and bone while the main target for calcitonin is the bone osteoclasts. insulin-stimulated pinocytosis of the insulin-receptor complex. A and B only. B. somatostatin E. CRH (corticotrophin releasing hormone) Ans: C . Which of the following statements is/are true? A. B. D. somatomedin c D. Down-regulation of insulin receptors is due to A. allosteric effector sites on an inactive enzyme. GnRH (gonadotropin releasing hormone) C. ribosomes and stimulating translation. B and C. Ans: E 54. insulin-stimulated release of inhibitory prostaglandins. D. a receptor that. adrenal corticosteroids regulate gene expression by binding to A. TRH (thyrotropin releasing hormone) B. The main actions of parathyroid hormone are to raise plasma calcium and lower plasma phosphate levels while the main action of calcitonin is to lower the plasma calcium level. irreversible binding of insulin to its receptor. For the most part. D. Regarding the endocrine system and hormone feedback. alpha-MSH (alpha-melanocyte stimulating hormone) C. beta-MSH Ans: D 58. E. testosterone and inhibin respectively B. The feedback of thyroid hormone is an example of a short-loop feedback system. The main organ of steroid catabolism is the adrenal gland. B. C. O-Hydroxylation of progesterone gives rise to A. deoxycorticosterone. cortisol and testosterone respectively E. the hormones of the endocrine system utilize positive feedback. estrogen and inhibin respectively D. deoxycortisol. D. All of the following biologically active peptides are potentially derivable from the pituitary K dalton glyco-protein proopiomelanocortin EXCEPT A. Ans: A 61. The feedback of insulin is an example of a long-loop feedback system. which of the following statements is false? A. The major precursor of urinary 17-ketosteroids is cortisol. B. dehydroisoandrosterone. beta-endorphin D. inhibin and activin respectively Ans: B 59. E. B. conjugations and a final breakdown of the steroid nucleus to acetoacetate. C. C. CLIP (corticotropin-like intermediate lobe peptide) B. inhibin and testosterone respectively C. angiotensin II E. Catabolism of steroids involves reduction. corticosterone.57. All of the above. cortisol. None of the above. . Ans: E 60. Regulation of FSH and LH secretion by the anterior pituitary is effected by A. Which of the following statements is CORRECT? A. increased activity of the desmolase complex E. Which one of the following would be ost useful in determining whether ovulation has occurred? A. all are potential mechanisms. Which of the following is a precursor of both adrenocortical and gonadal steroid hormones? A. Tight control of hormone levels and their actions is important in normal human homeostasis. estradiol D. Control of growth C. serum prolactin level Ans: B 66. increased blood flow B. testosterone Ans: D 63. Ans: C 62. Control of metabolism D. development of adrenal hypertrophy D. Control of extracellular fluid volume and composition E. None of the above.D. serum testosterone level E. Many hormones exert their feedback either directly on the gland that produces them. Control of differentiation B. Ans: D 64. corticosterone B. urinary 17-ketosteriod level B. depletion of cholesterol esters C. serum estradiol level D. cholecystokinin . All of the following are potential actions of hormones EXCEPT which one? A. preferential synthesis of progesterone Ans: E 65. ACTH has all of the following effects on the adrenal cortex EXCEPT which one? A. pregnenolone E. urinary gonadotrophin level C. A peptide hormone which is located both in the hypothalamus and in the pancreas is A. dihydroxycholecalciferol C. E. on a gland that controls their synthesis/secretion or some combination of these. activation of a G protein-coupled receptor. C. Ans: C 68. glucagon. phosphorylation of one or more proteins. Ans: A . E. parathyroid hormone. D. None of the above. proinsulin somatostatin neurophysin none of the above Ans: C 67. B. E. adrenocorticotrophic hormone. multiple protein-protein interactions. increased secretory vesicle trafficking. C. C. a soluble cytoplasmic polypeptide receptor for the steroid. melanocyte stimulating hormone. Ans: D 69. C. guanine nucleotide exchange. Each of the following is derived by the proteolytic processing of a larger protein molecule EXCEPT A. plasma-membrane associated receptor-adenylate cyclase complex. D. B. E. a steroid transport system coupled to a specific steroid hydroxylase. Ans: D 70. The pituitary hormone ACTH controls to a large part the biosynthesis of cortisol. Which of the following statements is CORRECT? A. D. growth hormone. Increased plasma cortisol levels inhibit the release of corticotropin releasing factors. The adrenal secretion of cortisol and the pituitary secretion of ACTH both depend on the secretion of corticotropin releasing factors by the hypothalamus. E. D.B. Signal transduction initiated by insulin leads to all of the following EXCEPT A. ability to carry out reverse pinocytosis. B. C. E. The feature of target cells for steroid hormones which gives tissue specificity for steroid hormone action is A. All of the above. B. cholesterol to phospholipid ratio of the plasma membrane. D. a flavoprotein. Can be replaced therapeutically by other mammalian growth hormones. All of the following statements regarding the second messenger concept of hormone action are true EXCEPT which one? A. renin to its active form Ans: B . bradykinin to an inactive form E. C. C. D. None of the above are exceptions. Human growth hormone (HGH). Angiotensin converting enzyme catalyzes conversion of A. Ans: C 74. Ans: C 73.20-desmolase are segregated to different compartments in the cell C. all statements are true. B. Causes an increase in the size of cells. angiotensinogen to angiotensin I B. the side chain cleavage complex that Catalyzes the conversion of cholesterol to pregnenolone requires NADPH. A. a P450. angiotensin I to angiotensin II C. most of the cholesterol used for steroid hormone synthesis comes from the plasma B. E. D. the enzymes for 17-alpha-hydroxylase and 17. and molecular oxygen D. Cyclic AMP is a leading candidate for the second messenger of lipid-soluble hormones such as steroids. B and C E. angiotensin II to angiotensin III D. in specific tissues A. in vivo. B. Which of the following statements concerning steroid hormone synthesis is correct A. Causes a decrease in the size of cells. The hormone itself is the first messenger. Hormones act through receptors to stimulate the production of the second messenger. increases the rate of cell proliferation.71. decreases the rate of cell proliferation. A and C Ans: E 72. although cells in the adrenal cortex can synthesize cholesterol. delta 4-androstenedione. polypeptide hormones cause a specific physiological response in target cells whereas steroid hormones simply stimulate target cells to divide. it lowers serum calcium levels and raises serum phosphate levels D. phosphodiesterase. it lowers calcium and phosphorus levels in plasma C. E. whereas steroid hormones do not. it stimulates reabsorption of phosphate from the kidney Ans: A 76. Ans: A 79. cGMP C. B. steroid hormones enter target cells. 5 alpha-dihydrotestosterone. B. steroid receptor protein E. A. nuclear hormone receptor. C. it causes (or enhances) precipitation of calcium salts in bone E. E. adenylyl cyclase. whereas polypeptide hormones do not. The mechanism of action of steroid hormones differs from that of polypeptide hormones in that A. B. In target sites such as prostate. inositol triphosphate (IP3) D. 17 beta-estradiol. its secretion is inhibited by high levels of plasma calcium B. A and B. D. Ans: E 78.75. C. The most prominent second messenger involved in the actions of LH. testosterone appears to act via one of its metabolites which is A. dehydroepiandrosterone. FSH and ACTH is A. Ca2+ B. and B and C. D. a 17-ketosteroid. . C. Which of these statements concerning parathyroid hormone (PTH) is CORRECT? A. polypeptide hormones interact with receptors. cAMP Ans: E 77. The biochemical mechanism by which parathyroid hormone exerts its effect on sensitive tissues is by activation of a(n) A. the difference between pregnenolone and progesterone is the presence of a hydroxyl group on C17 C. alpha-endorphin .g. Extracellular signaling. C. Intracellular signaling. beta-lipotropin D. Endocrine. voltage-gated Ca2+ channel. plasma membrane. androstenedione) has exactly 17 carbons B. Ans: A 83. Ans: A 82. cytoplasm. none of the above Ans: E 81. B. mitochondria. D. The receptor protein for steroid hormones occurs principally in the A. paracrine. a 17-ketosteroid (e. Which of the following statements concerning steroid hormones is correct A. beta-MSH E. removal of the C18 Carbon of corticosterone is an important step in the synthesis of aldosterone D. tyrosine kinase. ACTH B. Nerve impulse transmission. E. B. Beta-endorphin is derived fro A. methionine enkephalin B. neuronal.D. nuclear membrane. enkephalin C. D. All of the following biologically active peptides are potentially derivable fro betalipotropin (beta-LPH) EXCEPT A. and contact-dependent are all forms of A. C. Golgi membrane. gamma-endorphin Ans: C 84. aromatization of androstenedione produces beta-estradiol E. Hormone signaling. E. Ans: A 80. the lack of a methyl group at C-10. all of these. permits the processing of the growth factor to its active secreted form. beta-endorphin E. amines) A. form an irreversible complex with lipid-anchored peripheral membrane proteins. Testicular androgens Ans: E 88. diffuse to the nucleus and activate transcription factors. leads to the covalent attachment of the growth factor to its receptor. the 21 carbon steroid skeleton. B. Most water-soluble hormones (e. Chemically. C. beta melanocyte stimulating hormone (beta-MSH) D. Gonadotropin releasing hormone . D. Ans: C 87. Adrenal androgens E. is a means of desensitizing the receptor. antidiuretic hormone (ADH) Ans: E 85. the estrogens are characterized by A.C. D. Mineralocorticoids C. The phosphorylation of tyrosine residues on a growth factor receptor A. interact transiently with integral membrane proteins. B.. C. B. Which group of steroids in the male has a pronounced general anabolic effect? A. polypeptides. the aromatic character of the A ring. E. Ans: A 86. Estradiol B.g. the lack of a hydroxyl function at C-17. Glucocorticoids D. C. bind to heterotrimeric G proteins in the cell's plasma membrane. D. Ans: D 89. What molecule induces synthesis of progesterone receptors/ A. Estrogens B. generates interaction sites for SH2 domains on target proteins. decrease C. release of Ca2+ from the endoplasmic reticulum. activation of a phospholipase C isoform. They are never found in malignant cells. the nuclear membrane. RNA polymerase. B. Norepinephrine E. Ans: A . decreased synthesis of cAMP (3'. Ans: D 92. DNA. C. Ans: D 91. B. non-histone (acidic) protein. hydrolysis of cGMP (3'. Progesterone Ans: A 90. They may interact with sites on the chromatin to cause the expression of specific genes. Luteinizing hormone D. 5'-GMP). All of the following are true of estrogen receptors EXCEPT which one? A. D. D.C. phosphorylation of one or more proteins. B Ans: B 93. the next step in this signal transduction pathway is A. Tissue specificity in the action of steroid hormones is determined at the level of A. B. histone proteins. E. They are found only in target tissues. 5'-AMP). no effect D. E. How would inhibitors of protein synthesis be expected to affect the actions of a steroid hormone on its target cells? A. increase B. Following the binding of insulin to its receptor. D. C. C. They may enter the nucleus only when bound to steroid hormone. Progesterone receptor A. binds to heat shock proteins in the cytoplasm D. Estriol is found in the urine conjugated with A. taurine. E. Ans: C 96. Adrenocorticotropic hormone (ACTH) stimulates the conversion of cholesterol to pregnenolone through mechanisms involving cyclic AMP. C. The formation of pregnenolone from cholesterol is a rate controlling step in adrenal steroid hormone synthesis. C. Ans: A 95. have seven transmembrane domains. B. The reactions which lead to the formation of pregnenolone from cholesterol take place in mitochondria. D. protein. D. B. Progesterone is a precursor for aldosterone. possess intrinsic tyrosine kinase activity. Zinc finger domains are characteristic of hormone receptors that A. E. can be activated in the absence of progesterone by phosphorylation C. Progesterone is formed from pregnenolone through a series of hydroxylation reactions which require NADPH. D. Each of the following statements about adrenal cortical steroid hormones is correct EXCEPT which one? A. can bind to DNA in the absence of progesterone B. benzoic acid. regulate the flux of Ca2+ into the cytoplasm. all of the above . Ans: E 97. C. interact with heterotrimeric guanine nucleotide-binding proteins.94. contains a nuclear localization signal E. B. bind steroids. glycine. glucuronic acid. E. 3'. epinephrine. E. Luteinizing Hormone E. Oxytocin Ans: A 99. these two chains will readily recombine to form active insulin in high yield.Ans: E 98. Inhibin A D.5-trisphosphate. It is composed of two peptide chains linked by disulfide bonds. all B. only 1 and 2 Ans: A 101. 1. D. E. C. Chorionic Gonadotropin B. none C. D. Heterotrimeric guanine nucleotide-binding proteins (G proteins) usually function in signal transduction cascades by modulating the concentration of intracellular messengers. Which statement about insulin is not true? A. Intracellular messengers include all of the following EXCEPT A. When separated. Ans: C . B. It is synthesized as a precursor.2-diacylglycerol. C. Follicle Stimulating Hormone C. B. only 2 and 3 E. Ans: C 100. It promotes glucose and amino acid uptake by muscle. What molecule keeps the corpus luteum viable for several weeks after fertilization? A. only 1 and 4 D.4. It probably exists in a tightly folded conformation at physiological concentrations in plasma.5'-adenosine monophosphate.LH stimulates progesterone synthesis (3) FSH stimulates estradiol synthesis (4) steroid hormones fro the gonads feed back on the hypothalamus and pituitary Which of the statements are true? A. It is stored in the secretory granules of the beta cell of pancreatic islets as Zn-insulin along with an equimolar amount of C-peptide. The following statements are related to the endocrinology of reproduction (1) LHRH is synthesized in the hypothalamus (2). inositol 1. calcium ion. glucuronides of tetrahydro-derivatives involving ring A of the steroids originally secreted by the adrenal gland. norepinephrine Ans: C 104. C. Ans: B 106.and C-terminal amino acids B. an androgen. CRF B. glucuronide and sulfate conjugates of estrogens.102. is a tripeptide with blocked N. ACTH E. a mineralocorticoid. Proopiomelanocortin is a hormone precursor for hormones. GnRH D. a progestagen. a glucocorticoid. Thyrotropin Releasing Hormone (TRH) A. glucuronides of the steroid compounds originally secreted by the adrenal gland. Ans: B 105. is produced by the anterior pituitary gland to stimulate thyroid hormone release from the thyroid gland D. Why are all not expressed simultaneously? A. stimulates the release of TSH from the thyroid C. B. D. is found in highest concentration in the thyroid gland Ans: A 103. pregnanediol. E. The secretion of LH and FSH from the anterior pituitary is under the control of A. C. is derived form big ACTH biosynthetically E. Urinary end-products of glucocorticoid and mineralocorticoid metabolism consist largely of A. TRH C. D. There are tissue-specific degradative enzymes . unrecognizable small metabolic fragments of the original steroids which are produced by the liver. Aldosterone is A. B. β-arrestin B. Vitamin D may well be considered a hormone because it A. B. E. what binds to the receptor to block its interaction with Gs? A. is formed de novo in the body. After the β-adrenergic receptor is desensitized by phosphorylation. Hexagons and pentagons B. E. There are tissue-specific enhancers There are tissue-specific promoters There are tissue-specific processing proteases There are tissue-specific transcription factors Ans: D 107. requires modification in order to express physiological activity. The number of insulin receptors on a cell is regulated by the amount of insulin in the medium surrounding the cell. The effects of insulin upon cellular metabolism are directly related to the amount of insulin bound to receptors. Insulin exerts its biological effects by interaction with a specific receptor on the plasma membrane of cells. D. C. Squares and triangles E. The biological action of insulin requires that the molecule be transported to the cell interior. Inhibin B D. Gg C. is strictly steroid in nature. Ans: B . Ans: C 110. operates via the second messenger route. Pentagons and rectangles D. Which statement below regarding the biological action of insulin is incorrect? A. Hexagons and squares C. Isoproterenol E. What shape are the surfaces of a clathrin-coated vesicle? A.B. Triangles and pentagons Ans: A 108. B. D. D. albeit with the aid of light. C. C. Receptor α-subunit Ans: A 109. is soluble in lipid solvents. transduction of a signal by intrinsic tyrosine phosphorylation. acetyl-CoA. elevated transport of amino acids into the liver. tyrosine. All of the following statements concerning the synthesis of epinephrine are correct EXCEPT A. it requires tetrahydrobiopterin D. interaction of the receptor with a heterotrimeric G protein. C. increased activities of enzymes of the urea cycle. The identification of zinc finger domains in the structure of a hormone receptor would predict A. D. protein breakdown. All of the following effects Can be produced by elevated levels of glucocorticoids EXCEPT A. E. C. B. B. phenylalanine. E. binding of the receptor to double-stranded DNA. tyrosine hydroxylase catalyzes the rate-limiting step E. it occurs in the adrenal medulla B. E. it involves S-adenosylmethionine (SAM) Ans: B 113. it involves transamination C. . regulation of the receptor by receptor-mediated endocytosis. D. Ans: E 115. glutamate. D. D. increased net conversion of glucose to amino acids. Ans: D 112. C. C. Ans: A 114. B. carbohydrate metabolism. water intake. a decrease of muscle protein. elevated tyrosine transaminase. B. Aldosterone acts primarily in the regulation of A. amino acid adsorption. tryptophan. sodium balance. Catecholamines are synthesized in the brain fro A.111. E. E. Ans: E 118. 25-hydroxycholecalciferol in the kidney. Vitamin D. cortisol. D. Pro-ACTH is proteolytically cleaved into ACTH and another protein of unknown function. Pro-ACTH and Beta-LPH. Beta-LPH is proteolytic ally cleaved with one of the products being the endorphins. B. Cortisol C. Thyroid hormone Ans: C 117. if any. D. B. 25-hydroxycholecalciferol in the liver. 1. D. As regards the synthesis of ACTH.25-dihydroxycholecalciferol in the liver. C. Ans: E 119. Ans: C 120. None of the above. C. Glycosylated POMC is proteolytic ally cleaved into two proteins. B.25-dihydroxycholecalciferol in the kidney. It is initially synthesized as proopiomelanocortin (POMC). The major glucocorticoid in an is A. 11-desoxycortisol. forming covalent bonds with intermediates in metabolic pathways B. C. What hormone is excreted from the chromaffin cells of the adrenal medulla? A. ACTH B. is false? A. corticosterone. Epinephrine D. Oxytocin E. Hormones affect the rates of metabolic pathways by all of the following EXCEPT A. 1. (cholecalciferol) is converted into A.Ans: D 116. stimulating uptake of metabolites by cells . 1-hydroxycholecalciferol in the liver. aldosterone. which of the following statements. C. E. all recognize the same DNA response element. D. gluconeogenesis D. High levels of insulin and LDL have identical regulatory effects on the number of their respective cell surface receptors expressed by a cell. B. binding to specific receptors Ans: A 121. homologous up-regulation. by regulating transcription at the chromosomes. through chemical modification of ribosomes. by allosteric activation of protein kinases. homologous down-regulation. C. For both of these ligandreceptor systems this phenomenon is classified as A. and proteins. are membrane bound receptors for steroid hormones that signal ligand binding through a complex G-protein pathway. simultaneously bind hormones. Ans: B 123. stimulating the genome to produce specific transcripts D. none of the above. carbohydrate metabolism Ans: B 124. D. Steroid hormones are thought to function primarily A. putrefaction B. via the adenylate cyclase mechanism. B. by binding to a receptor-enzyme complex in the nuclear membrane. C. B. DNA. contain zinc finger DNA binding domains with Zn atoms coordinated by 2 cysteines and 2 histidine residues.C. The steroid hormone receptors A. Ans: B 122. Ans: A . heterologous down-regulation. heterologous up-regulation. D. Aldosterone is normally associated with partial regulation of what process? A. sodium balance C. lipid digestion E. activating protein kinases E. E. follitropin. secretion in the urine as steroid glucuronides and sulfates. degradation in liver into acetate. cAMP B. Concerning the anterior pituitary hormones. C. lutropin. Diacylglycerol D. . cGMP C. None of the above Ans: B 128. Two vitamins which can be considered to function in part as hormones are A. Vitamin D and Vitamin A C. Vitamin K and Vitamin E D. which one of the following statements is false? A. C.125. inositol phosphate E. excretion in urine as free steroids. prolactin and adrenocorticotropin. Vitamin A and Vitamin E E. What is the mechanism by which atrial natriuretic factor promotes phosphorylation of intracellular proteins? A. D. Overproduction of lutropin/follitropin is seen in Kallman's Syndrome which is characterized by failure to sexually mature and grow. steroid hormones are removed fro the circulation mainly by A. B. B. Thyrotropin stimulates the thyroid gland and is made up of an alpha subunit and a beta subunit but the beta subunit is the only one of the two subunits that is specific for thyrotropin. thyrotropin. Vitamin E and niacin B. The anterior pituitary makes six hormones. Somatotropin's main function of growth promotion is indirect via raising the levels of somatomedin c (insulin-like Growth Factor I). Production of the anterior pituitary hormones are all stimulated by releasing factors made by the hypothalamus and which are carried from the hypothalamus to the anterior pituitary via the blood. Ans: C 127. E. Tyrosine autophosphorylation Ans: B 126. somatotropin. D. E. binding first to a specific steroid receptor which then binds to the nuclear matrix and blocks mRNA degradation. salt balance. C. carbohydrate metabolism. Testosterone is a member of the C-l9 androgen class of steroids. salt balance D.testosterone in peripheral target tissues of the adult. C. estrogens B. Testosterone affects the rate of bone maturation. B. Ans: D 130. blood pressure B. conversion into bile acids. carbohydrate metabolism Ans: E 131. salt balance E. binding to and activating a previously synthesized but inactive enzyme. mineralocorticoids . response to stress. D. binding first to a specific steroid receptor which then binds to a specific hormonal control site on the DNA and activates transcription. A. Testosterone is converted to the more active 5-alpha-dihydro. glucocorticoids regulate gene expression by A. binding first to a specific steroid receptor which then binds to an inactive enzyme and causes activation. binding to the sigma subunit of RNA polymerase and stimulating transcription. urine output. E. Ans: A 129. One of the main functions of mineralocorticoids is to regulate while one of the main functions of the glucocorticoids is to regulate . Ans: B 132. Which one of the following statements concerning the metabolism of testosterone is FALSE? A. renin activity C. B. The rate of testosterone formation in the stroma of the ovary is regulated by the activity of side chain cleavage enzyme. In eukaryotic cells. After removal of the testes (castration) the granulosa cells of the adrenal Can compensate by the conversion of cholesterol to testosterone.D. Which group of adrenocortical steroids has a GENERAL catabolic effect (mainly protein depletion)? A. blood pressure. testicular androgens Ans: C 133. Ans: C 134. Multiple genes on different chromosomes E. insulin stimulates uptake of glucose into muscle and adipose cells. insulin stimulates triglyceride synthesis in adipose cells. B. insulin stimulates liver adenylate cyclase activity. adrenal androgens E. Another non-enkephalin gene is transcribed as part of its transcript B. All of the following are true with respect to the formation and function of insulin EXCEPT A.C. C. Leu-enkephalin gene is included in multiple repeats of met-enkephalin gene D. E. One gene with multiple copies of leu-enkephalin Ans: C . glucocorticoids D. What is unusual about the DNA coding of enkephalins? A. Proinsulin is mostly cleaved to form insulin in the beta cells of the pancreas. The effect of insulin on blood glucose levels is opposite that of epinephrine. D. It shows tissue-specific cleavage C. Proteoglycan monomers contain A. C. 6. glycosaminoglycans. D. when processed to the mature form. D. C. glucose. N-acetyl glucosamine. chondroitin sulfate A B. C. 7. glucuronic acid and N-acetylgalactosamine-4-sulfate. chondroitin sulfate B C. nucleus. D. Hyaluronic acid consists of repeating units of A. glucose and fructose. mannose. galactose and N-acetylgalactosamine. B. either mannuronic acid or iduronic acid. All of the following occur in the hexose monophosphate pathway for glucose metabolism EXCEPT A. B. cytosol. They are polyanions. derivatives of mannosamine. heparin D. mitochondria. nucleus and microsomes. repeating trisaccharide units. sialic acid. C. E. Which mucopolysaccharide contains alpha 1->4 glycosidic bonds? A. 5. D. . B. B. 4. B. They contain long chains of repeating disaccharides. The asparagine-linked oligosaccharides of mammalian glycoproteins. C. HMP shunt occurs in A. formation of C-7 sugar phosphates. hyaluronic acid E. E. fucose. reduction of NAD. D. glucuronic acid and N-acetylglucosamine. They generally form viscous solutions in water. Carbohydrate residues frequently are esterified with sulfate. 3. E.Chapter 16 Carbohydrate Metabolism II: Special Pathways and Glycoconjugates 1. may contain residues of each of the following EXCEPT A. B. They contain roughly equal amounts by weight of protein and carbohydrate. Which statement about proteoglycans is FALSE? A. dermatan sulfate 2. glucuronic acid and N-acetylgalactosamine. E. A nine carbon acid found in a terminal position in the oligosaccharide portion of many glycoproteins is A. D. biosynthesis of heparan.C. B. It is not sulfated 11. 9. NADP+ 10. xylose. 13. D. What makes hyaluronic acid different from the other 5 classes of proteoglycans? A. C. transaminase. B. D. 12. galactose. E. synthesis of glutathione. It is limited to animal tissue B. NAD+ E. glucuronic acid. It is not charged E. transhydrogenase. The bond linking chondroitin sulfate to protein in bovine cartilage involves a residue of A. Erythrose 4-phosphate + fructose 6-phosphate <--> sedoheptulose 7-phosphate + glyceraldehyde 3-phosphate This reaction is catalyzed by A. D. E. conversion of cysteine to taurine. N-acetylglucosamine. conversion to sulfite to sulfate. E. ADP C. B. gluconic acid. formation of C-5 sugar phosphate precursor of nucleotides. AMP D. sialic acid. C. reduction of NADP. synthesis of cysteine from methionine. B. C. Phosphoadenosine phosphosulfate (PAPS) participates in the A. It is not acetylated D. The principal regulatory factor governing the rate of the pentose phosphate pathway is the level of A. ATP B. . iduronic acid. hyaluronic acid. glucuronic acid. mannose. 8. release of C-1 of glucose as carbon dioxide. It is not a lubricant C. Krebs cycle D. glycolysis. a major source of energy is supplied to the body via oxidation of NADPH by the electron transport chain. transamidinase. 14. B. 1 B. D. C. electron transport. glucose-6-phosphate may be synthesized from pentose phosphates. generation of NADPH. D. the citric acid cycle. All of the following are accomplished by the hexose monophosphate shunt EXCEPT A. glucuronate. heparin. 100 E. hyaluronate. formation of ATP. B. synthesis of pentoses. D. 5 C. 17. B. E. pentoses may be converted into glycolytic intermediates and then to pyruvate. Glycolysis B. B. E. transaldolase. 15. the hexose monophosphate pathway. C. D. C. 19. Which of the following generates NADPH? A. The hexose monophosphate shunt pathway is utilized for all of the following EXCEPT A. E. 18. chondroitin sulfate. ribose 5-phosphate degradation. 50 D. What is the minimum number of carbohydrate residues that defines a protein as a glycoprotein? A. hexose may be converted to pentose. C. ribose 5-phosphate synthesis. transketolase. the urea cycle. hexose monophosphate shunt C. The carbohydrate used in the synthesis of nucleic acids in animals is produced in A. D.C. All of the following are glycosaminoglycans EXCEPT A. Gluconeogenesis . E. keratan sulfate. 500 16. Thiamine pyrophosphate participates in the reaction catalyzed by A.and O-linked carbohydrate residues on glycoproteins? A. 75 E. one mole of carbon dioxide and reduction of two moles of NADPH. glutamate. one mole of carbon dioxide and reduction of two moles of NAD. forms CO2 as glucose 6-phosphate is converted to pentose phosphates. 95 21. none of the above 25. converts lactate to pyruvate. pyruvate carboxylase. 55 D. B.E. The non-oxidative portion of the hexose monophosphate shunt A. one mole of ribose 5-phosphate. requires ATP. C. E. B. aspartate aminotransferase (GOT). can lead to synthesis of hexose phosphates from pentose phosphates. 24. one mole of fructose 6-phosphate and reduction of two moles of NADP. 5 B. glucosamine. D. one mole of ribulose 5-phosphate. one mole of xylulose 5-phosphate. N-linked has branches . isocitrate dehydrogenase. C. Glycogenolysis 20. E. transketolase. transaldolase. one mole of carbon dioxide and reduction of two moles of NADPH. What is the major difference in the synthesis of N. D. glutamine. 25 C. 22. 23. The nitrogen donor for amino sugars is A. B. D. What percentage of carbohydrate determines that a molecule is a proteoglycan and not a glycoprotein? A. C. The immediate products of oxidation of one mole of glucose 6-phosphate through the oxidative portion of the pentose phosphate pathway are A. does not function in mature erythrocytes. C. D. one mole of ribulose 5-phosphate. B. ammonia. E. one mole of carbon dioxide and oxidation of two moles of NADPH. E. C. Which enzyme catalyzes a decarboxylation? A. Which group of compounds are all intermediates in the hexose monophosphate shunt? A. fructose 6-phosphate. N-linked has mannose O-linked is assembled on a dolichol intermediate O-linked is assembled on the protein Synthesis of O-linked requires energy 26. ribulose 5-phosphate. gonads and adrenal tissue 28. sedoheptulose 7-phosphate. glucose 6-phosphate 27. 6-phosphogluconate dehydrogenase B. All of the following molecules are formed in the pentose phosphate pathway EXCEPT A. skeletal muscle E. C. adipose tissue C. B. 31. glycosaminoglycans.B. 6-phosphogluconolactone. 6-phosphogluconate. E. erythrose 4-phosphate. fructose 6-phosphate. glyceraldehyde 3-phosphate 30. The first intermediate formed from glucose in the pentose phosphate pathway is A. glucose 1-phosphate. ribose 1-phosphate. liver B.6-phosphate D. derivatives of mannosamine. red blood cells D. glucose 1-phosphate. D. B. fructose 1-phosphate. carbon dioxide B. NADH E. erythrose 4-phosphate. carbon dioxide E. either mannuronic acid or iduronic acid. C. Proteoglycan monomers contain A. E. glucose 6-phosphate dehydrogenase . glucose 6-phosphate. NADPH D. The hexose monophosphate shunt is least active in A. D. 29. ribulose 5-phosphate. pentose 5-phosphate C. D. repeating trisaccharide units. glycerol 3-phosphate C. fructose 1. xylulose 5-phosphate B. glucose 1-phosphate. The products of the pentose phosphate pathway include A. B. beta-hydroxybutyrate dehydrogenase E. E. the TCA cycle B. NADH and pentose phosphate. chondroitin sulfate and hyaluronate. all contain N-acetylgalactosamine D. all have 1 --> 4 linkages in them C. 6-phosphogluconate. B. C. C. 34. C. 36. 35. increased leakage of potassium into the cells. the associated hemolytic anemia is ultimately due to what changes from normal in red cells? A. All of the following are intermediates in the conversion of glucose to ribose EXCEPT A. sulfated N-acetylglucosamine residues. all of the following statements are true EXCEPT which ones? A. repeating trisaccharide units. B. D-ribulose 5-phosphate. ribose 5-phosphate. B. . Comparing keratan sulfate dermatan sulfate. all contain acetyl groups E. decreased concentrations of NADPH. The enzyme transaldolase is a component of A. the pyruvate dehydrogenase complex E. Hyaluronic acid is characterized by A. glucose 1-phosphate. C. citrate lyase 32. an intrinsic defect in membrane structure. E. the hexose monophosphate shunt C. decreased formation of ATP by mitochondria. all contain beta-glycosidic bonds 37. NADPH and carbon dioxide. D. D. In glucose 6-phosphate dehydrogenase deficiency. none of the above 33. D. beta-glycosidic bonds. glucose 6-phosphate. several polysaccharide chains attached to protein. decreased ability to carry out glycolysis. fatty acid synthase D. B. NAD+ and pyruvate.C. pyruvate kinase D. they all contain a uronic acid. . Proteoglycans A. Which of the following is NOT found as an intermediate or product of the pentose phosphate pathway? A. D. cytosol. none of the above 40. D. D. C. fatty acid synthase. FADH2. xylulose 5-phosphate D. NADPH B. ATP. All of the following statements about the phosphogluconate (pentose phosphate) pathway are correct EXCEPT which one? A. E. D. All of the following are reactants or products of the pentose phosphate pathway for glucose oxidation EXCEPT A. pentose phosphate and carbon dioxide. ribulose 5-phosphate C. glucose 6-phosphate. The pathway is important in red blood cells because a product of the pathway is required for maintaining the proper oxidation-reduction state. C. C. 42. the TCA cycle. 38. A carbohydrate containing 7 carbon atoms can be produced by this pathway. are composed of glycosaminoglycans covalently attached to a protein core through a N-glycosidic linkage to asparagine 43. The enzyme transketolase is a component of A.D. endoplasmic reticulum. NADH 41. 39. the pyruvate dehydrogenase complex. CO2. contain repeating trisaccharide units. B. C. C. usually contain either glucuronic acid or iduronic acid. containing 5 carbon atoms are absent from this pathway. D. lysosomes. B. A major product of the pathway is NADPH. nucleus. a certain 7 carbon sugar. mitochondria. E. B. The oligosaccharide moiety of glycoproteins is synthesized and processed in or on A. contain N-acetyl mannosamine. E. the HMP shunt. certain triose phosphates. B. ribose 5-phosphate E. B. phosphoenolpyruvate 2. B. All of the following substances are intermediates in the formation of glucuronic acid from glucose EXCEPT A. Protein chain B. C. CMP 4. 1 and 5 45. more sedoheptulose 7-phosphate than NADPH is required. chondroitin sulfate E. B. 47. dermatin sulfate E. Nacetylgalactosamine 5. D. B. Hyaluronic acid 48. C. Which of the following heteropolysaccharides is frequently used clinically as an anticoagulant? A. hyaluronic acid B. 6-phosphogluconate. Proteoglycan aggregates contain all of the following EXCEPT which one? A. UDP-glucuronic acid. more ribose 5-phosphate than NADPH is required. chondroitin sulfate 46. The precursors for the biosynthesis of N-acetylneuraminic acid include which two of the following? 1. more NADPH than ribose 5-phosphate is required. glucose 6-phosphate. 1 and 2 B. C. All of the following are products or intermediates of the hexose monophosphate pathway EXCEPT A. N-acetylmannosamine 3. Keratin sulfate C. ribulose 5-phosphate. carbon dioxide. A key enzyme in the pathway is glucose 6-phosphate dehydrogenase. D. UDP-glucose. UDP-galactose. 44. E. . Dermatan sulfate D. 49. the needs for NADPH and ribose 5-phosphate are balanced. glucuronic acid A. 3 and 4 D. 4 and 5 E. 2 and 3 C.E. keratin sulfate C. glucose 1-phosphate. The oxidative branch of the pentose phosphate pathway predominates over the nonoxidative branch when A. heparin D. hyaluronic acid B. chondroitin-4-sulfate C. dolichol phosphate D. All of the following glycosaminoglycans contains sulfate attached to a carbohydrate molecule except one. chondroitin sulfate . E. D. E. B. C. 50.D. thiamine pyrophosphate E. more NADPH than sedoheptulose 7-phosphate is required. Heparin 53. C. 51. 55. What is the exception? A. production of pentose phosphates. All of the following are products or intermediates of the hexose monophosphate shunt (pentose phosphate pathway) EXCEPT A. C. E. glycerol 3-phosphate. D. All of the following are directly associated with the pentose phosphate pathway EXCEPT A. In nature most mucopolysaccharides or glycosaminoglycans are found covalently linked to protein cores. B. glyceraldehyde 3-phosphate. NADPH. adenosine diphosphate B. 54. more NADPH than ribose 5-phosphate is required. more ribose 5-phosphate than NADPH is required. fructose 6-phosphate. glyceraldehyde 3-phosphate. coenzyme A C. NADH. Hyaluronic acid B. glucuronic acid 1-phosphate. phosphoenolpyruvate 52. D. carbon dioxide. A. B. a 4-carbon sugar phosphate. the needs for NADPH and ribose 5-phosphate are balanced. The core sugars of N-linked oligosaccharides are preassembled as a derivative of ______ prior to their transfer to a newly synthesized polypeptide. Which is not? A. The nonoxidative branch of the pentose phosphate pathway predominates over the oxidative branch when A. Dermatan sulfate D. synthesis of NADPH. ribose 5-phosphate. Keratan E. Nicotinamide adenine dinucleotides accept electrons from flavin adenine dinucleotides. C. Cytidine nucleotides are key intermediates in the synthesis of glycogen. erythrose 4-phosphate B. galactose and N-acetyl galactosamine B. both A and D 61. cysteine E. heparan sulfate 56. In the reaction below. NAD is a prominent acyl group transfer coenzyme. mannose and N-acetyl glucosamine C. E. the oxidized form of NADPH C. The isoalloxazine ring structure is found in coenzyme A. The inner core of N-linked glycoproteins contains which of the following sugar residues? A. heparin sulfate B. mannose and N-acetyl neuraminic acid 57. 6-phosphogluconate D. ribulose E. Sulfation of heparin occurs by means of sulfate transfer from by the action of a sulfotransferase. catalyzed by transketolase. Which of the following best indicates the products of the hexose monophosphate hunt? A. fucose and N-acetyl glucosamine E. The active glucosyl donor in biosynthesis . carbon dioxide and NADPH D. D. what is compound Z? Z + ribose5-P <--> glyceraldehyde-3-P + sedoheptulose-7-P A. B. Which statement is correct? A. mannose and galactose D. pentoses and carbon dioxide 60. xylulose 5-phosphate 59. 3'-phosphoadenosine-5'-phosphate D. NADH and pentoses E. A. GTP reacts with mannose 1-phosphate in the same way as UTP reacts with glucose 1-phosphate. fructose 6-phsophate C. 3'-phosphoadenosine-5'-phosphosulfate C. 58. dermatan sulfate E. ATP.C. heparin (mast cell) D. NAD and pyruvate B. A. E. B. B. Which of the following participates in N-acetyl neuraminic acid transfer reactions in man? A. dermatan sulfate B. dolichol phosphate. Formation of 6-phosphogluconolactone. chondroitin-4-sulfate E. C. CMP-N-acetyl neuraminic acid D. Release of C-6 of glucose as carbon dioxide. 63. Formation of C-7 monosaccharide phosphates. D. glucose-l-phosphate 3'-glucosyl-ATP UDP-glucose UDP-maltose UDP-glucose-6-diphosphate 62. UDP-alpha-D-N-acetyl neuraminic acid E. GDP-beta-D-N-acetyl neuraminic acid . N-acetyl glucosamine. activated sugars are initially transferred to and assembled on A. C. transaldolase D. GDP-alpha-D-N-acetyl neuraminic acid C. glucose 6-phosphate dehydrogenase E. C. heparan sulfate D. E. D. 6-phosphogluconate dehydrogenase C. Formation of C-5 monosaccharide phosphate precursors of nucleotides. coenzyme A. UDP-beta-D-N-acetyl neuraminic acid B. lactonase B. D. glycogenin. Reduction of NADP. chondroitin-6-sulfate 64. keratan sulfate C. Which of the glycosaminoglycans found in proteoglycan aggregates is devoid of uronic acid units? A. E. B. All of the following occur in the pentose phosphate pathway EXCEPT A. Which of the following is the first enzyme unique to the pentose phosphate pathway? A. In the biosynthesis of the N-linked oligosaccharides in glycoproteins. asparagine. phosphoglucoisomerase 66. 65. the reduction of NAD. B. pentose phosphate pathway C. UDP. D. B. CoA. the hexose monophosphate shunt is the principal source of A. fructose 6-phosphate.67. 70. provide ribose-5-phosphate for the synthesis of nucleotides D.iduronic acid D. glycogen synthesis 68. The repeating disaccharide units of glycosaminoglycans (mucopolysaccharides) are composed of a hexosamine residue and a uronic acid residue.glucuronic acid 71.galacturonic acid E. B. provide NADPH for ribonucleotide reductase for the synthesis of deoxy ribonucleotides . D. C. pantothenic acid. ribose 5-phosphate. N-acetyl-galactosamine-6-sulfate . gluconeogenesis D. D. E.glucuronic acid B. biotin. 69. vitamin C. Glucose 6-phosphate dehydrogenase catalyzes the first step in which of the following pathways? A. E. Thiamin-pyrophosphate. both c and d. carbon dioxide. 72. glycolysis B. provide NADPH for the synthesis of fatty acids and cholesterol C. the major component of cartilage proteoglycans? A. N-acetyl-galactosamine-6-sulfate . The activated form of glucose involved in the biosynthesis of glycoproteins. E. Which of the following is not a function of the pentose phosphate pathway? A. glucose 6-phosphate. HMP shunt requires A. N-acetyl-mannosamine-6-sulfate . Which is the correct disaccharide unit for chondroitin-6-sulfate. tricarboxylic acid cycle E. provide NAD+ for the oxidation of fatty acids B. magnesium ions. ascorbic acid. C.glucuronic acid C. ADP. galactose and glucuronic acid is a derivative of A. In liver. N-acetyl-glucosamine-6-sulfate . N-acetyl-glucosamine-6-sulfate . C. C. Which class of proteoglycans is most abundant in the body? A. All of the above are functions of the pentose phosphate pathway. transfer occurs within the endoplasmic reticulum. 74. produces pentoses B. Carbon number 1 of glucose in the hexose monophosphate shunt is converted to A.E. The transfer is made from a lipid intermediate called dolichol. C. carbon dioxide. ATP. B. D. 75. 77. What is a major function of the hexose monophosphate shunt? A. NADPH and carbon dioxide. produces ADP C. and Nacetylamino sugars. NADH and pentose phosphate. E. B. C. E. the GAGs are linked to serine residues in the core protein. The products of the pentose phosphate pathway include A. proteoglycans typically carry many negative charges. D. Dermatan sulfate C. The biosynthesis of dolichol-PP-oligosaccharide is inhibited by tunicamycin. fatty acid. C. pathway for glucuronic acid synthesis E. B. Hurler's disease results from deficient activity of an enzyme normally involved in the degradation of GAGs. The major sugar components of proteoglycans are pentoses. In proteoglycans. None of the above is correct.glucosamine (GlcNAc) residues. ribose. 73. such as xylose. chondroitin sulfate B. D. The oligosaccharide is built up on the protein beginning with attachments of GlcNAc to asparagine and subsequent additions of either GlcNAc or Man residues from the corresponding UDP sugars. 78. The oligosaccharide contains both mannose (Man) and N-acetyl. Which of the following statements about N-glycosylation of proteins is FALSE A. Keratan sulfate . Heparin D. B. deoxyribose. produces NADH D. D. NAD+ and pyruvate. Hyaluronic acid is a glycosaminoglycan (GAG) but not a proteoglycan. Which statement is FALSE? A. Heparan sulfate E. pentose phosphate and carbon dioxide. 76. a condensing enzyme.3-trimyristoylglycerol 4.2-dimyristoylphosphatidylserine D. the double bonds are separated by one methylene group. 3. The first double bond is between carbons 2 and 3. none of the above. NADH and NADPH D. During the biosynthesis of saturated fatty acids. a transacylase. brain. The reductive steps in fatty acids synthesis are carried out by A. Fatty acid oxidation is a major source of energy in all of the following tissues EXCEPT A. The double bonds are in a very stable conjugated system. Storage. FADH2 and NADH B. D. oleate. C. C. 1. Which of the following is true about polyunsaturated fatty acids found in man? A. NADH C. B. 6. and Utilization of Fatty acids and Triacylglycerols 1.Chapter 17 Lipid Metabolism I: Synthesis. Generally. the addition of every two-carbon unit requires A. The fatty acid synthase complex contains all the following EXCEPT A. a carboxylase. the highest yield of ATP on a mole per mole basis? A. 2 NADH + 2 H+ + 1 ATP . D. B.2. a reductase. upon oxidation. kidneys. palmitoleate. 5. liver. D. The double bonds are generally TRANS. resting skeletal muscle. Complete hydrogenation of linoleate produces A. B. palmitate. D. E. E. C. myristate (14:0) B. myristoyl-CoA C. NADPH 7. heart muscle. a dehydratase. 1. E. 2. C. stearate. Which of the following compounds will generate. B. In contrast to fatty acids. Each round of synthesis adds two carbons from malonyl-CoA to the methyl end of the fatty acid chain. carried by albumin in blood B. pancreatic lipase. lipoprotein lipase. small intestine. phospholipase A2. 2 NADPH + 2 H+ + 1 ATP 1 NADPH + H+ + 1 ATP 1 NADH + H+ + 1 FADH2 + 1 ATP 1 NADPH + H+ + 1 FADH2 + 1 ATP 8. 9. C. brain. E. D. malic enzyme. B. adipose tissue. E. C. E. The major site of the formation and release of acetoacetate is A. which of the following is characteristic of ketone bodies? A. malate dehydrogenase. ATP-citrate synthase. glycerol kinase. It utilizes acetyl CoA from carbohydrates and occurs in the liver and adipocyte inner mitochondrial matrix. D. C. D.B. The final product contains the original two carbons E. The rate limiting step involves a reaction in which acetyl CoA accepts a one carbon group from another acetyl CoA to form malonyl CoA. The enzyme primarily responsible for generating acetyl-CoA in the cytoplasm is A. . Fatty acid synthase is a complex enzyme in humans which is active as a homodimer. B. contain an average of 18 carbon atoms E. Acetyl CoA carboxylase is active only in its multimeric form which contains biotin in a N-carboxybiotin-enzyme complex. hormone-sensitive lipase. D. C. acetyl-CoA carnitine transferase. The acyl carrier protein (ACP) in the fatty acid synthase enzyme contains a biotin moiety esterified to a hydroxyl group of serine to provide the sulfhydryl group onto which the growing fatty acid chain is always attached. C. B. E. D. ATP-citrate lyase. 10. B. require carnitine for transport into mitochondria D. liver. soluble in water C. Mobilization of fat from adipose tissue requires the enzymatic activity of A. may be saturated or unsaturated 11. True statements about de novo fatty acid synthesis include A. muscle. 12. phosphatidic acid ---> diacylglycerol + Pi. Acyl carrier protein C. 18. Neither 17. B. diacylglycerol + fatty acyl-CoA ---> triacylglycerol + CoA. 16. All of the following are directly involved in the conversion of fatty acids and glycerol to triglycerides EXCEPT A. requires NADP in one of the steps. 3. Which of the following molecules possesses a phosphopantetheine group? A. occurs in the mitochondrial matrix. E.5 C. L-beta hydroxyacyl-CoA dehydrogenase 19. 2. E. produces only acetyl-CoA. Both D. arachidonate. occurs only in skeletal and heart muscle. occurs in the cytosol. NAD. 2. B. enoyl-CoA isomerase D. The predominant fatty acyl group in stored triglycerides is A.0 B.13. D. acyl-CoA dehydrogenase E.25 E. The theoretical P/O ratio for the oxidation of a fatty acid to acetyl-CoA is A. phosphatidylcholine + diacylglycerol ---> triacylglycerol + lysophosphatidylcholine. enoyl-CoA hydratase B. 0. 0 14. fatty acid + ATP + CoA ---> fatty acid-CoA + AMP + PPi. L-beta-ketoacyl-CoA thiolase C. A specific phosphatase. linoleate. D. C. Acyl-CoA's. B.0 D. Acetyl CoA B. Phosphatidic acid. C. monoacylglycerol + fatty acyl-CoA ---> diacylglycerol + CoA. B. C. D. The beta-oxidation of oleic acid (delta-9) as opposed to palmitic acid requires the addition of which of the following enzymes? A. The beta-oxidation of fatty acids A. ATP. . 15. E. A reaction for the synthesis of triacylglycerol believed to be unique in the intestine is A. E. C. ribose 5-phosphate B. pyruvate B. How may of the carbon atoms from stearic acid may contribute. increased lipolysis in adipose tissue.C. alpha-glycerol phosphate D. 17 C. A condition which favors increased ketone body synthesis is A. ketone body formation. oleate. increased fatty acid synthesis in liver. stearate 20. increased glycogenolysis in skeletal muscle. Acetyl-CoA for de novo fatty acid biosynthesis is formed by the energy-dependent cleavage of A. Glucose metabolism is necessary in adipose tissue to supply which of the following for the formation of triglycerides? A. cholesterol side-chain cleavage. D. 6 D. 3 E. beta-hydroxybutyrate dehydrogenase. B. succinate dehydrogenase. alpha-ketoglutarate dehydrogenase. B. B. Each of the following processes occurs predominantly in mitochondria EXCEPT A. through cellular metabolism. glutamate dehydrogenase. D. acetoacetate 23. phosphoenolpyruvate 22. succinyl-CoA C. citrate D. palmitate. D. oxaloacetate C. 24. to the net synthesis of glucose? A. decreased gluconeogenesis in liver. 21. tricarboxylic acid cycle reactions. 0 25. E. fatty acid biosynthesis. alpha-ketoglutarate E. . NADH dehydrogenase. C. C. The function of fatty acyl-CoA dehydrogenase of beta-oxidation is most analogous to that of A. D. 18 B. E. L-beta-hydroxyacyl-CoA dehydrogenase . D. E. yields 38 equivalents of ATP. highly insoluble. 3 cis --> 2 trans enoyl-CoA isomerase D. 26. E. C. cytosol. mitochondria. Enoyl-CoA hydratase B. Oxidation of acetoacetic acid to carbon dioxide and water A. 30. requires an investment of two equivalents of ATP. highly oxidized. endoplasmic reticulum (microsomal fraction). E. requires NADPH. is increased during fasting. B. The synthesis of fatty acids by the de novo pathway from acetyl-CoA A. C. Lipids are the most efficient forms of biologically stored energy because they are A. lysosomes. C. lysosomes. D. C. E. D. endoplasmic reticulum. Golgi apparatus. All of the following enzymes are involved in the beta-oxidation of palmitic acid EXCEPT A. requires transfer to the CoA residue of succinyl-CoA. 27. Enzymes for the synthesis of oleic acid from palmitic acid are located in the A. B. utilizes acetoacetyl-CoA as substrate for beta-ketoacyl reductase. B. ATP and bicarbonate. D. occurs primarily in mitochondria. by the liver mitochondria follows its direct reaction with CoA-SH. converted directly to ATP. B. D.E. proceeds by the reversal of beta-oxidation. Acyl-CoA dehydrogenase E. Acyl-CoA thiolase C. B. C. takes place preferentially in the brain. De novo fatty acid biosynthesis occurs in the A. mitochondria. 31. oxidative phosphorylation. highly soluble. nucleus. highly reduced. 29. cytosol. 28. modulation of polypeptide secretion from hypothalamus. stimulate the synthesis of ketone bodies. Coenzyme A. Carnitine is involved in all of the following processes EXCEPT A. inhibiting delta9-desaturase. inhibiting carnitine acyltransferase. C. cofactors or intermediates in the synthesis of triglyceride EXCEPT which one? A. E. 36. formation of an ester bond with fatty acids. oxygen. E. D. B. C. transport of citrate from mitochondria for synthesis of malonyl-CoA in the cytosol. NADPH. Fatty acyl-CoA C. 37. . stimulate fatty acid oxidation leading to a decreased rate of gluconeogenesis. stimulation of ketone body utilization by brain. All of the following compounds are normally involved as a substrates or cofactors in the conversion of extramitochondrial palmitic acid to oleic acid EXCEPT which one? A. CDP-diglyceride E. 34. promotion of increase in skeletal muscle mass. D. malonyl-CoA. C.32. increase the concentration of mitochondrial acetyl CoA available for combustion through the TCA cycle. B. C. All of the following molecules are either substrates. inhibition of insulin secretion from pancreatic beta cells. water 35. D. B. D. B. Citrate regulates fatty acid metabolism by A. 33. Phosphatidic acid D. inhibiting acyl-CoA synthetase. turn back fatty acids heading for the mitochondrion while stimulating fatty acid elongation in the endoplasmic reticulum. carnitine. E. activation of triacylglycerol synthesis in adipose. stimulate fatty acid oxidation leading to a decreased rate of gluconeogenesis. B. The most immediate impact of malonyl CoA inhibition of carnitine: fatty acyl CoA transferase is to A. use of fatty acids released from adipose tissue for generation of energy in other tissues. the transport of fatty acyl groups across the inner mitochondrial membrane. Glycerol 3-phosphate B. The primary action of leptin is the A. maintenance of separate pools of coenzyme A in the mitochondrial matrix and the cytosol. E. C. E. malonyl-CoA. 38. B. Free fatty acids C. C. 8 FADH2 and 8 NADH C. All of the above are ketone bodies. 14 NADPH D. acetoacetate. is constant. 16 NADPH E. C. stimulating fatty acid synthase. An intermediate produced during the oxidation of palmitic acid to carbon dioxide and water in skeletal muscle mitochondria is A. acetoacetyl-CoA. alpha-ketoglutarate. E. NADH D. C. as the degree of unsaturation increases the yield of ATP A. A diglyceride E. Carbon Dioxide 43. . 7 NADPH 42. stimulating acetyl-CoA carboxylase. All of the compounds listed below are ketone bodies EXCEPT which one? A. Pantothenate E. With respect to the complete oxidation of fatty acids. propionyl-CoA. Phosphatidic acid D. ATP C. B. All of the following are intermediates or enzymes in the production of triglycerides in a cell of fatty tissue from a lipoprotein of blood plasma EXCEPT which one? A. biotin B. 39. The β-oxidation of a 16 carbon fatty acyl CoA to 8 acetyl CoAs would generate: A.D. Fatty acyl-CoA transferase 40. All of the following are involved in processes related to fatty acid synthesis EXCEPT which one? A. pyruvic acid. Hormone sensitive lipase B. B. 41. hydroxymethyl-glutaryl-CoA D. acetone. beta-hydroxybutyrate. slightly decreases. 7 FADH2 and 7 NADH B. E. slightly increases. D. acetoacetic acid E. They are solid at body temperature. hydration and cleavage. E. liver. C. malic acid 47. hydrogenation. hydrogenation and cleavage. C. E. Their specific gravity is higher than that of water. Which one of the following is an example of precursor (feedforward) activation? The effect of A. malonyl CoA on carnitine acyl transferase I. B. The sequence of reactions for the beta-oxidation of fatty acids is A. C. The coenzyme involved in the synthesis of malonyl-CoA from acetyl-CoA is A. dehydrogenation. reaches a maximum with three double bonds. 44. insulin on hormone-sensitive lipase. 48. D. dehydrogenation. B. C. adipose tissue. dehydrogenation and cleavage. activation. Which of the following is a property of the triacylglycerols? A. succinyl-CoA C. depends upon the tissue. activation. oxidation. biotin. activation. skeletal muscles 45. citrate on acetyl CoA carboxylase. dehydrogenation and cleavage. hydration. Those occurring naturally with an asymmetric carbon atom are by convention named as if they derive from L-glyceraldehyde. 49. They are resistant to attack by alkali. malonyl-CoA B. . phosphatidic acid D. thiamine. nicotinamide. riboflavin. In man the synthesis of fatty acids from glucose proceeds primarily in the A. D. D. D. kidney. hydrogenation. E. hydration. dehydrogenation. B. E. activation. palmityl CoA on acetyl CoA carboxylase.D. intestines. 46. B. activation. Which of the following provides reducing equivalents for the formation of NADPH in the cytoplasm? A. B. C. hydration and cleavage. D. folic acid. Among the differences between fatty acid synthesis and fatty acid oxidation is the fact that A. oxaloacetate C. uses NADH as the source of reducing equivalents. CH3(CH2)18 COOH E. Fatty acid synthesis A. is the main use of energy and reducing equivalents provided by glycolysis in red blood cells. The correct structure for palmitic acid is A. B. E. None of the other answers is correct. 55. the acyl groups form different thioesters in synthesis and oxidation. occurs in the mitochondria of the cell. synthesis is accelerated and oxidation depressed in diabetes. C. transport of citrate from mitochondria. malonyl-CoA D. .50. NADPH + H+ and malonyl-CoA. A. transport of oxaloacetate from mitochondria. CH3(CH2)16 COOH D. pyruvate 52. B. D. E. 51. D. but not in synthesis. CH3(CH2)14 COOH C. NADPH + H+. synthesis occurs in the mitochondria and oxidation in cytosol. D. E. malonyl-CoA is an intermediate in oxidation. requires that the growing hydrocarbon chain be attached to acyl carrier protein. D. synthesis of acetoacetate from acetyl-CoA in mitochondria. citrate B. B. Which of the following is the most active positive effector of acetyl-CoA carboxylase? A. Elongation of an acyl-CoA derivative in mitochondria requires NADH + H+ and acetyl-CoA. malonyl-CoA and ATP. C. E. requires the intermediate synthesis of HMG-CoA to begin the process. B. a specific carrier for acetyl-CoA in the mitochondrial membrane. C. synthesis uses NADH and oxidation uses FAD. Export of acetyl-CoA from mitochondria to cytosol to participate in fatty acid or steroid biosynthesis involves A. NADPH + H+ and acetyl-CoA. CH3(CH2)12 COOH B. NADH + H+ and malonyl-CoA. C. 53. ADP E. formation of acetyl-carnitine. 54. palmitic acid. 58. B. Functional mammalian fatty acid synthase is composed of: A. acyl-CoA dehydrogenase. linoleic acid. energy-dependent carboxylation of carnityl-CoA. E. This system utilizes both NADH and NADPH as sources of reducing equivalents. D. oleic acid. with each subunit catalytically functioning independently B. transfer of a fatty acyl group from the sulfhydryl group of fatty acyl-CoA to the sulfhydryl group of carnitine. citrate B. D. acyl-CoA synthetase. Neither 59. thiolytic cleavage. palmitoleic acid. A dimer of identical subunits. Which of the following is the best positive effector of acetyl coenzyme A carboxylase? A. energy dependent formation of a thioester bond between the carboxyl group of a fatty acid and the sulfhydryl group of acyl carrier protein. oxaloacetate C. This system utilizes only NADH as a source of reducing equivalents. Carnitine acyltransferase catalyzes the A. B. C.56. Which of the following statements regarding the fatty acid elongation system located in the endoplasmic reticulum is CORRECT? A. A dimer of identical subunits. B. Both D. C. 57. stearic acid. E. D. All of the following fatty acids are synthesized in man EXCEPT A. with the subunits forming two catalytically active sites in the region where the subunits interface. This system only elongates saturated long chain fatty acyl-CoA derivatives. transfer of a fatty acyl group from the sulfhydryl group of fatty acyl-CoA to the secondary hydroxyl group of carnitine. 61. ATP is required for fatty acid oxidation for the reaction catalyzed by A. 60. This system utilizes only NADPH as a source of reducing equivalents. B. transfer of a fatty acyl group from the sulfhydryl group of fatty acyl-CoA to the carboxyl group of carnitine. malonyl coenzyme A . E. Acetyl-CoA is the source of the two-carbon unit that is added to the carboxyl end of the fatty acid being elongated. C. carnitine acyltransferase. D. C. C. What is the rate limiting step in the conversion of triglyceride to free fatty acids in adipose tissue? A. a decreased synthesis of phospholipids in the endoplasmic reticulum. 65. are converted to malonyl-CoA. the electron donor for the last reductive step in the elongation of the carbon chain of a fatty acid is A. D. malonyl-CoA inhibits carnitine acyltransferase I. 66. D. D. increase the NAD/NADH ratio. a decreased synthesis of fatty acyl adenylate in the mitochondria. E. Hydrolysis by the hormone stimulated lipase. occurs primarily in the nucleus. proceeds through successive shortening of the fatty acids by three-carbon units. None of the above. NADPH. E. 67. an increased level of fatty acid in the cytoplasm. B. C. FMNH2. does not produce useful energy for the cell. begins with the fatty acid thioester of CoA. 63. C. an increased level of fatty acyl pantetheine in the mitochondria. FADH2. Fatty acids with an odd number of carbon atoms and certain branched-chain fatty acids can support the net synthesis of glucose because they A. B. beta-oxidation of fatty acids is inhibited. In mitochondria. pyruvate 62. the pool of acetyl-CoA is depleted by the TCA cycle and fatty acid biosynthesis. E. C. yield NADPH on oxidation. coenzyme Q-2H. Stimulation of lipoprotein lipase. high levels of ATP inhibit phosphofructokinase. E. The diffusion of glycerol into the blood. is inhibited by carnitine.D. C. B. ADP E. D. The formation of Cyclic AMP. NADH. When fatty acid biosynthesis is stimulated. B. A deficiency in carnitine will result in A. a decreased level of fatty acyl CoA in the cytoplasm. D. are converted to acetoacetate and beta-hydroxybutyrate. The oxidation and degradation of fatty acids in the cell A. C. E. B. B. This inhibition occurs mainly because A. C. 64. can produce methylmalonyl-CoA which is converted to succinyl-CoA. . riboflavin and ascorbic acid. Mobilization of stored triacylglycerols from adipose tissue. 73. 17 C. pyruvate dehydrogenase. 3 E. Beta oxidation of long chain fatty acids. none of the above. B. B. acetyl-CoA carboxylase. provides NADPH. 6 D. A deficiency of carnitine would be expected to interfere with which of the following? A. D. E. The rate-limiting step of fatty acid synthesis is catalyzed by A. C. through cellular metabolism. malic enzyme. pantothenic acid and cholecalciferol. Which of the following is an 18 carbon fatty acid with 3 double bonds? A. palmitic acid B. Ans: C 71. B. citrate-cleavage enzyme. C.D. important in membrane structure. D. arachidonic acid 69. E. 18 B. the main source of odd chain fatty acids. Transport of fatty acids into adipose cells. D. degradation of fatty acids. 72. C. The synthesis of palmitate. 68. E. coenzyme A and thiamine. thiolase . to the net synthesis of glucose? A. oleic acid C. How may of the carbon atoms from stearic acid may contribute. What is the main function of beta-oxidation? A. linolenic acid E. E. high levels of citrate stimulate acetyl-CoA synthase. D. production of carbon dioxide. 0 70. B. oxidation of ethanol to acetic acid. riboflavin and niacin. linoleic acid D. Two vitamins important in beta-oxidation are A. C. B. C. decreased levels of plasma leptin. The biosynthesis of triacylglycerols in adipose requires A. E. which of the following reactions must occur? A. D. D. In order for acetoacetate to be utilized by extrahepatic tissues. propionyl-CoA carboxylase. E. D. B. B. D. C. 77. is stimulated by insulin. reduction to beta-hydroxybutyrate D. none of the above. E. requires the action of hormone-sensitive lipase. 75. increased levels of plasma glucagon. 78. decarboxylation of acetoacetate to form acetone B. HMG-CoA reductase. C. What is the maximum percentage of carbon atoms of glucose that can be used for synthesis of palmitic acid? A. citrate. C. carboxylation of acetoacetate C. acetyl-CoA carboxylase (malonyl-CoA synthase). In liver. Lipolysis: A. acetyl-CoA. acetoacetate may be preferentially A. decreased activation of long-chain fatty acids. increased glycerol secretion from adipose. B. D.74. oxidized to 2 moles of acetate. A metabolite which helps regulate which process will predominate is A. esterified to coenzyme A. reduced to beta-hydroxybutyrate. fatty acid synthase. transfer of a coenzyme A from succinyl CoA to form acetoacetyl CoA E. C. E. The committed step in fatty acid biosynthesis is catalyzed by A. requires an apolipoprotein. is inhibited by glucagon. apoprotein B. increased glucose uptake by adipose. fatty acyl carnitine. fatty acyl coenzyme A. malonyl coenzyme A. condensation with acetyl CoA to form HMG CoA 79. B. results in an increase in blood concentrations of esterified fatty acids. Fatty acyl coenzyme A may be used for triglyceride biosynthesis or fatty acid oxidation. 100% . 76. 80. dehydrogenase. B. lauric. always unsaturated. usually unsaturated. C. D. synthetase. hydratase.B. NAD. thiolase. caprylic. water. C. malonic acid B. B. D. 75% 66-2/3% 50% 33-1/3% 81. D. succinyl-CoA 83. C. 85. equally likely to be saturated or unsaturated. C. usually saturated. always saturated. . NADP. All of the following would be directly involved in oxidizing a long chain saturated fatty acid to carbon dioxide and water EXCEPT A. Coenzyme A. Position number one in the triglycerides of man is filled by a fatty acid residue that is A. The steps of beta-oxidation parallel portions of: A. B. 3-hydroxy-3-methylglutaryl-CoA D. Gluconeogenesis B. The most prevalent saturated fatty acid in animal fat is A. mevalonic acid C. E. Krebs cycle D. 86. B. Glycolysis C. racemase. E. Oxidative phosphorylation E. Pentose phosphate shunt 84. FAD. D. The formation of acetoacetic acid from acetyl-CoA involves which of the following compounds as an intermediate? A. E. Metabolic cleavage of acetoacetyl-CoA to two molecules of acetyl-CoA is catalyzed by a A. E. 3-hydroxybutyryl-CoA E. 82. the concentration of enzyme-bound biotin equals the carbon dioxide concentration. represent the main component of storage lipids. methyl malonyl-CoA 92. D. and ATP concentrations are all saturating. succinyl-CoA C. or neutral fats. only in the brain. fatty acids with an odd number of carbon atoms D. phosphatidic acid D. are the most abundant members of the acyl glycerols. myristic. only in the cytosol. are composed of three fatty acids in ester linkage to a glycerol molecule. B. Triglycerides A. 87. B. albumin in blood. B. E. since Vmax. acetyl-CoA carboxylase is present in excess of acetyl-CoA. E. saturated fatty acids C. initial rates are measured at any acetyl-CoA concentration. All of the other answers are correct. The maximal velocity (Vmax) of the acetyl-CoA carboxylase reaction would be obtained when A. palmitic. malonyl-CoA E. D. is independent of substrate concentration. the acetyl-CoA. C. hormone-sensitive lipase in adipose. D. Which of the following is an intermediate in fatty acid synthesis in the cytoplasm? A. the reaction is first-order with respect to acetyl-CoA. only in mitochondria. only in microsomes. E. B. . Medium-chain triacylglycerols may be an appropriate dietary supplement for an individual with a deficiency of A. C. C. carnitine in skeletal muscle. 90. malonyl-CoA B. unsaturated fatty acids B. acetoacetic acid E. malic acid 89. fatty acid oxidation in cardiac muscle. The elongation of fatty acids occurs A. C. carbon dioxide.C. in both mitochondria and microsomes. D. Propionyl carboxylase is an enzyme required for the oxidation of A. stearic. 91. D. but not Km. 88. propionyl-CoA is not completely oxidized to carbon dioxide and water. Acetoacetate is NOT oxidized to C02 in A. 95. hormone sensitive lipase. acyl carrier protein. intermediates of propionyl-CoA metabolism uncouple oxidative phosphorylation. 94. C. 8 moles of ATP. 0 moles of ATP. E. Oxidation of an odd-numbered chain fatty acid can be expected to yield proportionately less ATP than that of an even-numbered chain fatty acid because A. D. 5 moles of ATP. oxidation of propionyl-CoA requires energy input from ATP at a carboxylation step D. low density lipoprotein in blood. None 99. propionyl-CoA cannot be metabolized. B. The conversion of n moles of acetyl-CoA to 1 mole of palmitoyl-CoA (C16:0) requires A. D.E. PEP (phosphoenolpyruvate) carboxykinase C. brain. B. 3 B. E. long chain fatty acids are attached to . pyruvate dehydrogenase B. serum albumin. 7 moles of ATP. C. liver. Which enzyme or process requires the presence of acetyl-CoA in the cytosol? A. synthesis of ketone bodies D. reversal of the citrate synthase reaction E. B. The mobilization of triglyceride fatty acids from adipose tissue and their subsequent oxidation by muscle mitochondria involves all of the following EXCEPT A. acyl-CoA synthetase. how many of the carbon atoms of glucose could maximally contribute to the net synthesis of fatty acid? A. ATP: citrate lyase 96. 93. skeletal muscle. C. C. D. 98. All D. heart. For transport across the inner mitochondrial membrane. 4 C. B. 97. Considering the principal pathways involved. carnitine. nervous tissue. a hypercaloric-high carbohydrate diet. acyl transacylase. E. B. D. 103. phosphatidylethanolamine. low plasma levels of free fatty acids. Triacylglycerols are transported in the blood bound to albumin. occurs in response to increased dietary absorption in the small intestine. Both D. D. C. high intracellular levels of citrate. a hypercaloric-high protein diet. Triacylglycerols contain 3 fatty acids esterified to a glycerol backbone. An increased synthesis of acetoacetate and 3-hydroxybutyrate by the liver A. The oxidative decarboxylation of malate by the malic enzyme B. C. propionyl CoA carboxylase C. Triacylglycerols are the major storage form of fatty acids. acetyl-CoA with acyl-CoA dehydrogenase. E. 104. acetyl-CoA with carnitine acyl transferase I. 100. A portion of the NADPH necessary for fatty acid biosynthesis is provided by: A. B. Which of the following statements about triacylglycerols is not true? A. E. . acetyl CoA carboxylase E. acyl transferase. acetyl-CoA with carnitine acyl transferase II. B. malonyl-CoA with carnitine acyl transferase II. C. depends upon increased glycogenolysis in the liver. coenzyme A. citrate lyase B. acyl carrier protein 105. E. Triacylglycerols are an efficient storage form of energy. Neither 101. citrate synthase D. C. 102. carnitine. B. malonyl-CoA with carnitine acyl transferase I. The process of long chain fatty acid oxidation in liver is regulated in part by the interaction of A. D. D.A. B. All of the following conditions or factors would promote de novo fatty acid synthesis EXCEPT A. Triacylglycerols can be hydrolyzed to provide a gluconeogenic substrate. a high glucagon/insulin ratio. The pentose phosphate pathway C. Which of the following participates with human palmitate synthase as part of the same polypeptide chain? A. adenylate cyclase. desaturation D. synthesis of fatty acids in liver. reflects decreased energy demand by skeletal muscle during exercise. D. C. synthesis of glucose in liver. E. pancreatic lipase. brain. provides erythrocytes with an alternative metabolic fuel. B. C. All of the following processes or reactions are involved in the conversion of acetylCoA to oleic acid EXCEPT A. B. 110. biotin and folic acid C. 109. triglyceride lipase. C. D. . B. striated muscle. Pyridoxine and thiamine E. elongation E. oxidation of glucose in adipose tissue. Niacin and riboflavin D. phosphorylation C. D. synthesis of amino acids in liver. oxidation of fatty acids in erythrocytes. Plasma triglycerides can be hydrolyzed to fatty acids by the enzyme A. E. cytosol. Physiological conditions which promote the synthesis of ketone bodies would also promote the A. E. is sustained by increased triacylglycerol hydrolysis in adipose tissue. Which of the groups below contains two compounds that are parts of coenzymes involved in the beta-oxidation of fatty acids? A. Acetyl-CoA carboxylase is primarily located in the A. dehydration 108. Vitamin D and pantothenic acid B. The enzyme that catalyzes the reaction: Acetoacetate + Succinyl-CoA <----> Acetoacetyl-CoA + Succinate is essentially absent in the A. B. lipoprotein lipase. D. 106. E. cardiac muscle.C. liver. endoplasmic reticulum. carboxylation B. heparin. Choline and carnitine 111. kidney 107. enoyl-ACP hydratase.0 C. 3. thiolase. enoyl-ACP reductase. C. enoyl hydrase. 2. The carbon chains of fatty acids. 114. acyl dehydrogenase. 3-hydroxyacyl dehydrogenase. enoyl-ACP hydratase. beta-ketoacyl reductase. malonyl transferase. In mitochondrial oxidation of arachidonate to two carbon units all the following enzymes are used EXCEPT A. enoylACP reductase. enoyl-ACP hydratase. C. D. can produce fatty acid with an odd number of carbon atoms. B-hydroxy acyl CoA dehydrogenase. . beta-ketoacyl synthase. acyl dehydrogenase. This involves successive reactions catalyzed by four enzymes. B. beta-ketoacyl synthase. C. enoyl-ACP hydratase. beta-ketoacyl-ACP reductase. enoyl hydrase. thiolase.0 E. malonyl transferase. plasma membrane. enoyl hydratase. are shortened by two carbon atoms at a time. 112. 1. enoyl-ACP hydratase. thiolase. A fatty acid 10 carbons long can theoretically form how many moles of acetoacetate from the 2 carbon units directly generated during its breakdown? A. 3. acyl dehydrogenase. Fatty acid synthase A. D. beta-ketoacyl synthase.5 D. as CoA derivatives. 3-hydroxyacyl dehydrogenase. E. malonyl transferase. beta-ketoacyl reductase. The order of reactions in fatty acid biosynthesis is A. enoyl hydrase. lysosomes. E. B. 2. lipoxygenase E. enoyl-ACP hydratase. enoyl-ACP reductase. mitochondria. is found in the adipose tissue but not in the liver. E.5 B. D. enoyl-ACP reductase. C. These act in which order? A. beta-ketoacyl synthase.C. beta-ketoacyl synthase.5 113. D. 3-hydroxyacyl dehydrogenase. B. enoyl-ACP reductase. 3-hydroxyacyl dehydrogenase. acyl dehydrogenase. beta-ketoacyl reductase. produces mainly palmitate as the product. enoyl CoA isomerase. thiolase. B. produces oleic acid by skipping a reductive step. 115. is found in the mitochondria of cells. D. 116. acyl CoA dehydrogenase. enoyl hydrase. malonyl transferase. beta-ketoacyl reductase. fatty acids A. B. The activity of palmitoyl-CoA dehydrogenase. E. pancreatic lipase. E. The fatty acids carried in the blood by serum albumin under fasting conditions are most likely derived from the action of A. Both D. Rate of formation of palmitoyl-CoA. C. E. In mammalian fatty acid synthase. acyl dehydrogenase. 120. Covalently attaches to a serine hydroxyl group at a site on one subunit of the enzyme and is then transferred to the -SH of a phosphopantetheinyl group of the acyl carrier protein on the second subunit of the enzyme. 118. 117. malonyl CoA provides a malonyl group which: A. 3-hydroxyacyl dehydrogenase. B. The activity of carnitine-palmitoyl-acyl transferase-I. requires acyl carrier protein. requires malonyl-CoA. fatty acid synthase. can be synthesized from excess dietary carbohydrates or protein. The concentration of acetoacetyl-CoA. D. The mitochondrial system of chain elongation for fatty acids A. citrate synthase. cholesterol esterase. C. C. . 122. thiolase. acetyl-CoA carboxylase. Fatty acid synthesis is primarily controlled by regulation of A. D. B. Neither 119. pyruvate carboxylase. glucose 6-phosphate dehydrogenase.E. beta-keto fatty acyl ACP reductase. B. enoyl hydrase. D. utilizes NAD. 121. The concentration of cytosolic carnitine. lipoprotein lipase. containing double bonds cannot be synthesized. D. C. Which one of the following factors is considered to be rate limiting in the oxidation of palmitic acid in liver? A. adds two carbons at a time to the methyl end of a fatty acid. utilizes acetyl-CoA. hormone sensitive lipase. B. E. C. are not required at all in the diet. B. Covalently attaches to a serine hydroxyl group at a site on one subunit of the enzyme and is then transferred to the -SH of a cysteine group of the condensing enzyme domain on the same subunit of the enzyme. In humans. C. D. must be supplied entirely in the diet. E. other than palmitate, must be supplied in the diet. 123. In the absence of glucose uptake in adipose tissue there is A. net synthesis of triglycerides because glycerol accumulates. B. net synthesis of triglycerides because fatty acids accumulate. C. release of fatty acids because fatty acid oxidation is inhibited. D. a decrease in triglyceride synthesis because there is a deficiency of glycerol phosphate. E. None of the other answers is correct. 124. All of the following are involved in the conversion of pyruvate to a long chain saturated fatty acid EXCEPT A. malonyl-CoA. B. NADPH. C. carbon dioxide. D. acyl carrier protein. E. cyclic AMP. 125. Glycerol 3-phosphate in adipose tissue arises primarily from A. reduction of dihydroxyacetone phosphate. B. hydrolysis of phosphatidic acid. C. phosphorylation of glycerol by glycerokinase. D. selective uptake from blood. E. reduction of glyceraldehyde 3-phosphate. 126. Regarding triacylglycerol (TG) breakdown/hydrolysis, which one of the statements is false? A. Pancreatic lipase hydrolyzes TG in the intestinal lumen to 2-monoacylglycerols plus two fatty acids and its activity is enhanced by colipase. B. There is a hormone sensitive lipase in adipocytes whose function is fatty acid mobilization. C. Fatty acid mobilization via this enzyme can be altered as the diet is changed. D. Glucagon stimulates this hormone sensitive lipase by inhibiting adenylate cyclase and lowering cAMP allowing the enzyme to become dephosphorylated which, is its active form. E. Of the fatty acids eventually released from total hydrolysis of TG in the adipocyte, some enter the blood as free fatty acids where they bind albumin and are carried to other tissues such as muscle. 127. The reduction of which intermediate in glycolysis leads directly to a compound involved in the biosynthesis of fats? A. Fructose 1,6-diphosphate B. Glucose 6-phosphate C. Pyruvic acid D. Dihydroxyacetone phosphate Chapter 22--Gluconeogenesis, Glycogen Metabolism, and the Pentose Phosphate Pathway Key 1. Gluconeogenesis is the synthesis of: A. glucose from non-carbohydrate precursors. B. glycogen from glucose. C. pyruvate from glucose. D. fatty acids from glucose. E. glucose from fatty acids. 2. The pentose phosphate pathway is an important source of ____, and for ____, an essential precursor for ATP, NAD+, FAD, CoA, DNA and RNA. A. ATP; NADH B. NADH; NADPH C. NADPH; ribose-5-phosphate D. ribose-5-phosphate; ATP E. all are true 3. All are substrates for gluconeogenesis EXCEPT: A. glycerol. B. lactate. C. acetate. D. pyruvate. E. most amino acids. 4. The major tissues carrying out gluconeogenesis are the ____ and ____. A. brain; muscles B. muscles; kidneys C. liver; kidneys D. liver; red blood cells E. red blood cells; brain 5. Glucose monitoring devices use the reaction, Glucose + O2 + H2O ® gluconate + 2 ____, which is catalyzed by the enzyme ____. A. H2O; glucose hydrolase B. H2O; glucose oxidase C. H2O2; peroxidase D. H2O2; glucose oxidase E. H2O; gluconate synthase 6. In the gluconeogenic pathway, the three regulated reactions of glycolysis catalyzed by ____, ____ and ____ are replaced by alternative reactions. A. glucokinase; PFK-1; pyruvate kinase B. phosphoglucoisomerase; PFK-1; pyruvate kinase C. PFK-1; triose phosphate isomerase; pyruvate kinase D. glucokinase; PFK-1; glyceraldehyde-3-phosphate dehydrogenase E. glucokinase; PFK-1; pyruvate carboxylase 7. All of the following enzymes are unique to gluconeogenesis EXCEPT: A. phosphoglucoisomerase B. glucose-6-phosphatase C. pyruvate carboxylase D. fructose-1,6-bisphosphatase E. PEP carboxykinase 8. All are required for pyruvate carboxylase EXCEPT: A. biotin covalently linked to the enzyme. B. thiamin pyrophosphate (TPP). C. ATP. D. acetyl-CoA as an allosteric activator. E. tetrameric enzyme in the mitochondria. 9. In the pyruvate carboxylase catalyzed reaction, bicarbonate is "activated" by attachment to the ____ of ATP to form ____. A. b-phosphate; carbonyl ADP B. a-phosphate; carbonyl AMP C. a-phosphate; carbonylphosphate D. g-phosphate; carbonylphosphate E. g-phosphate; carbonyl AMP 10. The reaction sequence for the pyruvate carboxylase catalyzed reaction is: A. B. C. D. E. formation of N-carbonyl biotin attack of HCO3- on ATP liberation of Pi formation of carbonylphosphate C-3 carbanion of pyruvate attack on N-carbonyl biotin A. B, D, A, E, C B. B, D, A, C, E C. D, C, B, E, A D. D, B, C, A, E E. E, C, B, A, D 11. If levels of ____ and/or ____ are low, pyruvate is directed primarily into ____; but if they are high, pyruvate is converted into ____ for gluconeogenesis. A. NADH; ATP; glycolysis; OAA B. ATP; NADPH; glycolysis; acetyl CoA C. ATP; acetyl CoA; TCA cycle; OAA D. NAD+; acetyl CoA; TCA cycle; acetyl CoA E. ATP; acetyl CoA; glycolysis; malate 12. All of the enzymes of gluconeogenesis may be found in the cytosol EXCEPT ____ which is only found in the mitochondria. A. PEP carboxykinase B. pyruvate carboxylase C. fructose-1,6-bisphosphatase D. glucose-6-phosphatase E. all are only in cytosol 13. Pyruvate carboxylase consumes a(n) ____ to drive a carboxylation so that ____ could use the energy from decarboxylation to facilitate formation of PEP. A. NADH; pyruvate dehydrogenase B. NADH; lactate dehydrogenase C. ATP; pyruvate kinase D. ATP; PEP carboxykinase E. GTP; nucleotide diphosphate kinase 14. The primary regulatory point of gluconeogenesis is ____. A. glucose-6-phosphatase B. fructose-1,6-bisphosphatase C. fructose-2,6-bisphosphatase D. pyruvate carboxylase E. PEP carboxykinase 15. Which of the following reactions represents the gluconeogenic reversal of PFK-1 in glycolysis? A. fructose-6-P + ADP ® fructose + ATP B. fructose-6-P + H2O ® fructose + Pi C. fructose-1,6-bisphosphate + ADP ® fructose-6-P + ATP D. fructose-1,6-bisphosphate + H2O ® fructose-6-P + Pi E. none of the above 16. The endoplasmic reticulum bound enzyme that hydrolyzes glucose-6-phosphate to glucose in liver is: A. glucokinase. B. glucose oxidase. C. hexokinase. D. phosphoglucomutase. E. glucose-6-phosphatase. 17. Glucose-6-phosphatase is located in the ____ and produces ____ in vesicles that diffuse to the ____ releasing their contents into the blood stream. A. mitochondria; lactate; cytosol B. cytosol; glucose; plasma membrane C. endoplasmic reticulum; glucose-6-phosphate; cytosol D. endoplasmic reticulum; glucose; plasma membrane E. cytosol; glucose-6-phosphate; endoplasmic reticulum 18. Gluconeogenesis is not simply reversal of glycolysis since 2 pyruvate ® glucose requires ____ of combined ATP and GTP. A. 2 B. 3 C. 4 D. 5 E. 6 4)glucanotransferase. converts glucose to lactate. activates E. F-2. oligo(a1. A.4® a1. b-amylase. NAD+/NADH ratio D. oligo(a1. A. activates. the liver ____ because it has a typically high ____.6)-transglycosylase E. activates. C. A. shares the load of exercising muscle. ____ phosphorylates and thus ____ the enzyme PFK-2 which simultaneously ____ F-2. oligo(a1. phosphoglucomutase B. burns fat. PFK-2. F-2. ATP E. A. F-2. activity is reduced in highly branched regions of polysaccharides and stops four residues from any branch point. catalyzes hydrolysis of a (1®4) linkages in starch. galactose C. high concentrations of acetyl-CoA B. 24. inhibits.4®1. D. All are true for a-amylase EXCEPT: A. low levels of ATP C. a(1®6)glucosidase D. acetate level B. fructokinase 22. B. debranching enzyme. In the Cori cycle. UDP-glucose pyrophosphorylase C. cAMP-dependent protein kinase. a(1®6)glucosidase E.6-BPase B. amylo-(1.6)glucanotransferase.6-BPase E. a(1®6)glucosidase B. fructokinase. inhibits D. high levels of TCA cycle intermediates E.6-BPase. glycogen synthase D. a-amylase. debranching enzyme.6-bisphosphate (F-2. inhibits. PFK-2. adenylate cyclase. oligo(a1.4® a1. none of the above require energy input . a-amylase. is an important component of saliva and pancreatic juice. PFK-2 C.6-BP) are controlled by the tandem enzyme ____ and ____. cAMP-dependent protein kinase. Cellular levels of fructose-2.6-BPase. E. Which of the following is absolutely essential for the activation of pyruvate carboxylase? A. inhibits B. PFK-1 D. a(1®6)glucosidase C. b-amylase. Limit dextrins are degraded by the action of ____ which has two distinct enzymatic activities known as ____ and ____. The energy input for the synthesis of glycogen occurs during which of the following enzyme catalyzed steps? A. NAD+/NADH ratio 20.4)glucanotransferase. high levels of oxaloacetate D. catalyzes hydrolysis of a (1®6) linkages in amylopectin.19. converts lactate to lactose. activates 23. a-amylase. high levels of citrate 21. shares the load of exercising muscle. activates C. activates. catalyzes hydrolysis of a (1®4) linkages in glycogen.4)glucanotransferase 25.4® a1.4® a1. cAMP-dependent protein kinase. adenylate cyclase. PFK-1. AGEs generated by elevated blood glucose contribute to circulation.6-bisphosphatase E. inhibits glycolysis. A. non-reducing end of maltose. stimulates glycogen breakdown in liver. hexokinase. glycogen synthase. joint and vision problems of diabetics. 32. C. AGEs mean advanced glycation end-products. glucokinase D. fructose-1. blood glucose concentration over this last month. B. inhibits glycogen phosphorylase . E. The initiation of glycogen synthesis occurs by transfer of glucose from UDP-glucose to the: A. present blood glucose concentration. stimulates active transport of glucose and amino acids into muscle and adipose tissues D. stimulates glycogen synthesis in muscle and liver. 27. stimulates fructose-1. none are true. glycogen phosphorylase. glycogen phosphorylase. C. glycogen synthase E. Physiological effects of insulin include all EXCEPT: A.26. 29. D. Which of the following effectors is required for glycogen synthase activity when the enzyme is phosphorylated? A. and: A. average glucose concentration in the blood over the past several months. glucose-6-phosphate C. D. tyrosine-OH group of glycogenin.6-bisphosphate D. B. glucokinase. B. 2-position of fructose. 28. fructose-2. Glycated hemoglobin in a patient is an indication of blood glucose levels over the past few months. D. serine-OH group of glycogen synthase. E. stimulates gluconeogenesis. UDP-glucose 31. AGEs alter the function of the protein to which they are attached.6-bisphosphate E. A blood test for "Glycated hemoglobin" can determine the: A. inhibits phosphoprotein phosphatase-1. induces synthesis of glucokinase. glycogen synthase C. C. Glycogen synthesis and degradation must be carefully controlled at ____ and ____ to properly serve the metabolic needs for the organism. 4-position of free glucose. hexokinase 30. D. level of AGEs in the blood stream. glucose-1-phosphate B. stimulates glycogen synthesis B. AGEs form by enzyme catalyzed Schiff base formation between sugars and proteins. B. PFK-1 and pyruvate kinase C. C. Insulin in the bloodstream is a response to increased blood glucose. All are characteristics of AGEs EXCEPT: A. E. hexokinase B. E. As a result. phosphoprotein phosphatase-1. substrate-level phosphorylation. E. B. A. 38. Among the many physiological changes elicited by epinephrine. 39. C. All are physiological changes initiated by glucagon EXCEPT: A. activation of glycogenolysis in liver. activation of glycogenolysis in liver. C. Which of the following occurs in the muscle as a result of cortisol? A. long-term maintenance of steady-state levels of glucose in the blood stream. uses NADP+ as a coenzyme. stimulation of glycolysis by 2000 fold. An individual with von Gierke's disease lacks the enzyme ____ which is a liver enzyme used to maintain ____. phosphate addition. all are true. fat B. liver glycogen. activation of the urea cycle D. NADH D. D. blood glucose. strongly inhibited by [NADPH]. blood glucose. weak 34. NADPH C. TPP-assisted decarboxylation. glucose-6-phosphatase. all are true 35. D. E. E. B. E. B. activation of glycogenolysis in muscles. located in the mitochondria. hypoglycemic D. all of the above 37. C. ADP E. glycogen synthase. hypoglycemic E. glucose-6-phosphate preferentially goes to the pentose phosphate pathway. the patient is ____. D. stimulation of liver gluconeogenesis. D. Characteristics of glucose-6-phosphate dehydrogenase include all EXCEPT: A. A. forms a cyclic ester (lactone) of 6-phosphogluconate. inhibition of glycogen synthase. none of the above .33. ATP B. weak C. inhibited by fatty acid-CoA. The 6-phosphogluconate dehydrogenase reaction is an example of ____ and results in the production of ____. glycogen synthase. glucose-6-phosphate dehydrogenase activity is dependent upon use of some of the NADPH before activity increases. glucose-6-phosphate dehydrogenase will be turned on most of the time. increased degradation of muscle protein E. activation of glycogenolysis in muscles. activation of gluconeogenesis B. ATP levels. muscle glycogen. oxidative-decarboxylation. glucose-6-phosphate is rate limiting for pentose phosphate pathway. B. The ratio of NADP+/NADPH in liver runs about 1/67 which means that: A. increased glycogen synthesis C. the initiation of the adenylyl cyclase cascade includes all EXCEPT: A. 36. glucose-6-phosphatase. it is similar to the ratio of NAD+/NADH. C. PFK-1 E. phosphopentose epimerase. transferases E. II. transfer of keto groups from C-2 to C-3. phosphoglycerate isomerase C. ligases 44. B. E. B. I only B. glyceraldehyde-3-phosphate dehydrogenase D. phosphoglucoisomerase E.40. transfer of xylulose-5-phosphate into ribulose-5-phosphate. Transketolase is an enzyme that catalyzes: A. aldose reductase. transfer of ketoses into aldoses. isomerases C. glucose-6-phosphate dehydrogenase. hydrolases D. phosphopentose isomerase. fructose-6-P + glyceraldehyde-3-P Û xylulose-5-P + erythrose-4-P erythrose-4-P + fructose-6-P Û sedoheptulose-7-P + glyceraldehyde-3-P sedoheptulose-7-P + glyceraldehyde-3-P Û ribose-5-P + xyulose-5-P A. I and III E. transfers of three-carbon units from a ketose to an aldose. phosphoglucomutase B. II and III C. The polyol pathway is a suspected pathway for diabetic induced cataract formation and involves the enzyme: A. transaldolase. II only D. oxidoreductases B. D. D. UDP-glucose epimerase B. Transketolase belongs to what class of enzymes? A. Phosphopentose isomerase is quite similar to the reaction and mechanism of the ____ catalyzed reaction. E. phosphopentose epimerase D. The transaldolase catalyzed activity is similar to what glycolytic enzyme? A. I and II 45. C. all are similar 41. aldolase . enolase C. 42. III. Which of the following reactions is catalyzed by a transketolase in the pentose phosphate pathway? I. A. TPP-dependent transfer of 2-carbon units to the recipient aldose. C. 43. E. succinate E. both b and c will occur E. B. Which of the following results when glucagon binds to its receptor? A. 3 Gluc-6-P + 6 NADP+ ® 6 NADPH + 3 CO2 + 2 Fruc-6-P + 1 glyceraldehyde-3-P C. alanine B. The appropriate sequence for the transketolase catalyzed reaction would be: A. glycerol D. 4 Fruc-6-P + 2 glyceraldehyde-3-P ® 6 ribose-5-P B. D. C. which of the following best represents the net reaction of the pentose phosphate pathway? A. If NADPH is needed for biosynthetic reactions but ribose-5-P is not needed. glycolysis is activated B. C D. glucose-6-phosphate dehydrogenase is activated. E E. A. D. the non-oxidative enzymes produce pentose phosphates from fructose-6-phosphate and glyceraldehyde-3-phosphate. but no additional NADPH: A. A. the oxidative and non-oxidative enzymes of the pentose phosphate pathway are active. C. C. D. B. E. B. B. all of the above 49. reactive enamine attack on the aldehyde group of an aldose b-cleavage of Schiff base intermediate to release an aldose formation of Schiff base intermediate of a new ketose active site lysine forms Schiff base with keto-carbonyl group Schiff base hydrated to ketose and enzyme A. B. C. A 47. A. C. 48. C. none are true. D. B. C.46. E. glutamic acid C. E. D. B. Gluc-6-P + 2 NADP+ ® 2 NADPH + CO2 + ribose-5-P D. gluconeogenesis is inhibited 50. D. None of the above . E B. glycogen synthesis is inhibited E. A. When a cell with the pentose phosphate pathway has need for more pentose phosphates . the citric acid cycle is inhibited D. all enzymes of glycolysis and pentose phosphate pathway are active. protein synthesis is activated C. E. D. Which of the following can be used as a substrate for gluconeogenesis in the liver? A. All of the following are in the mitochondria EXCEPT: A. . Reduction involves the ____ of electron(s). gain. 5. Where does the energy that drives ATP synthesis come from? A. B. E. The oxidation states of the complexes. A.Chapter 20--Electron Transport and Oxidative Phosphorylation Key 1. proton-gradient. and NADH-dependent ATP synthesis is the result of ____ phosphorylation. C. substrate-level B. the electron transport complexes. a. substrate-level. C. D. electron C. concentration of the species being reduced D. oxidative E. creatine kinase. substrate-level. electron D. concentration of the species being oxidized C. loss. and reactions for which the standard cell potential is ____ are spontaneous under standard conditions. standard cell potential B. b. none of the above 3. A. E. NAD+ and FAD. adenylate kinase. a and b only E. Spontaneity of a redox reaction depends upon each of the following EXCEPT: A. B. loss. oxidative. oxidative 2. negative B. The electron gradient. positive C. ATP made in glycolysis and the TCA cycle is the result of ____ phosphorylation. oxidative. negative D. D. pentose phosphate pathway. Molecular oxygen. enzymes for fatty acid oxidation. gain. The proton gradient. positive E. and c 4. cytochrome c. D. All are characteristics of inner mitochondrial membranes EXCEPT: A. B. and as such. E. D. contains specific transport proteins. C. contains porin in high concentration. E. A. Complex I and Complex II produce a common product which is: A. standard free energy change for a redox reaction is related to the number of electrons transferred C. a half-reaction involving the loss of electrons is an oxidation reaction E. B. all are correct. for redox reactions with negative standard cell potentials. reduced O2. cytochrome c1. membrane lipids have mostly unsaturated fatty acids. 9. C. all are true. All are linked to the electron-transport chain through Complex I accepting electrons from NADH EXCEPT: A. 11. glycolysis. negative. Each of the following regarding redox couples is true EXCEPT: A. fatty acid oxidation. 12. reducing C. E. TCA cycle. 7. standard reduction potentials are measured relative to a standard hydrogen cell (H +/H2) B. folds into cristae. coenzyme Q. oxidizing D. reduced coenzyme Q. Fe-S centers. C. NADH is a strong ____ agent. reduced cyt c. . B. all are true statements 8. All of the following are membrane bound EXCEPT: A.6. and the substance oxidizing it D. B. NAD+. standard free energy change for a redox reaction is related to the standard cell potential B. for cells in which electrons flow toward the sample half-cell. Compounds with a large ____ reduction potential have a strong tendency to undergo oxidation. redox reactions must occur in pairs. can't be determined from information given 10. C. oxidizing B. where the total number of electrons involved in the oxidation equals the total number involved in the reduction E. reducing E. standard free energy change is negative D. D. FAD. gluconeogenesis. cytochrome a/a3. Each of the following is a true statement EXCEPT: A. E. positive. positive. the reduction potential is positive C. negative. a redox couple consists of a substance being oxidized. D. all are true statements. cyt c1. UQ. UQ. E. 18. complex II C. cyt bL E. cyt bH D. E. can easily diffuse in the membrane. complex IV 15. one. shuttle from complex I and complex II to complex IV. "proton pump. complex I B. NADH D. cyt c1 .-. two. In the first phase of the Q cycle. cyt c1 C. FAD B. [FMN]. NAD+ E. fatty acyl-CoA dehydrogenase-transferring protein. A. sn-glycerolphosphate dehydrogenase. releasing ____ H+ to the intermembrane space leaving ____ that transfers a second electron to ____. 4Fe-4S clusters. Rieske protein.-. All of the following are properties of coenzyme Q EXCEPT: A. Which complex reduces molecular oxygen? A. cyt bH. Which of the following is a two-electron donor? A. cyt c 17." 16. cyt c. C. UQH/UQH2 pool E. E. UQH2 transfers one electron to ____ and then to ____. B. succinate dehydrogenase (complex II). Rieske protein. D. Rieske protein. UQ. 14. complex III D. D. NADH-CoQ reductase (complex I). hydrophobic. cyt bL. All are flavoproteins EXCEPT: A. one. C. one. UQ. Complex I contains all of these components EXCEPT: A. two. UQ. D. cyt c1.-. B. three oxidation states. Rieske protein. 2Fe-2S clusters. Fe-S C. isoprenoid tail. cytochrome c. C. coenzyme Q-cytochrome c oxidoreductase (complex III). B. cyt bH B.13. cyt bL. two. D. B. two. four. H2O. inner. All of the following take place in the Q cycle EXCEPT: A. cytochrome c. E. C. E. transfer of electrons from bL to bH. B. UQ. NAD+. . 23. Cyt bL. C. water soluble. heme iron coordinated with histidine nitrogen and methionine sulfur atoms. The final electron acceptor in the electron transport chain is: A. protons C. electrons B. Complex III takes up ____ proton(s) on the matrix side of the ____ membrane and releases ____ protons on the intermembrane side for each pair of ____ passed through the Q cycle. molecular oxygen. Rieske protein Fe-S clusters. two. C only D. UQH2. B. inner. all are true. B. E. A only B. Cyt bH. none are true 22. D. E. protons D. globular with planar heme group near the center of the protein. Cyt c1. B only C. All are single-electron carriers EXCEPT: A.19. UQ Cyt c Complex III A. A. two. Which of the following is/are mobile electron carrier(s)? A. C. inner. 20. one. one. C. four. an electron is passed from bH to UQ. two protons are pumped into the matrix. C. 24. B. accepts electrons from cyt c1. D. one UQH2 is returned to the pool. an electron is passed from bL to UQ. All are characteristics of cyt c EXCEPT: A. outer. D. B & C E. electrons E. A & B 21. sn-glycerolphosphate dehydrogenase. C. succinate-CoQ reductase. 2 & 4 D. 2. C. H2O E. D. 1. E. All of the following transfer electrons to the UQ/UQH2 pool EXCEPT: A. cytochrome c oxidase.25. cytochrome bc1 complex. four D. B. NADH-CoQ reductase. FADH2 29. CuB. Cyt c1. Complex IV. NADH D. 3. 1. 4. CuA. E. three C. 4 only E. C. 1 & 2 C. D. Another name for complex II (succinate dehydrogenase) in the electron transport chain is: A. B. 28. Complex I. 26. 30. UQH2 C. two B. Cyt a. fatty acyl-CoA dehydrogenase. E. Complex II. D. The complete reduction of one molecule of oxygen gas requires how many electrons? A. Cyt a3. cytochrome c B. cytochrome c reductase. B. eight E. all of the above . Complex I Complex II Complex III Complex IV A. Which of the following complex(es) translocate protons in the inner mitochondrial membrane? 1. What molecule is the electron donor to complex III? A. six 27. 3 & 4 B. All are components of cytochrome c oxidase (complex IV) EXCEPT: A. b. g. D. E. c. proton gradient generated to produce ATP. the F0 subunit is hydrophilic. B. B. 35. a. B. it is proposed that ____-subunits form a rotor that turns with respect to ____-subunits and the ____-subunit is anchored to the rotor. All are characteristics of the binuclear center of complex IV EXCEPT: A. B. C. T-sites bind ATP. g E. catalyzes ATP hydrolysis as well as ATP synthesis. A. E. consists of five different kinds of subunits. one site contains ADP and Pi (L-sites). 32. c. a.31. T-sites become O-sites. Cyt a3 is a component. a. Fe-S is a component. b-subunits have catalytic sites for ATP synthesis. Two electrons are transferred to bound O2. D. 33. C. g B. c. beta-subunits have the catalytic site for ATP synthesis. D. all are true. D. a C. All are characteristics of the binding charge mechanism EXCEPT: A. the F1 subunit is attached to the integral membrane protein F0. C. C. 34. protons driven into the matrix. cyt c moving in the intermembrane space.and b-subunits are homologous. water is released here. one site is empty (O-sites). E. a. C. b. the ring of c subunits form a rotor with respect to the alpha subunits. B. g 36. D. four independent mobile complexes. b. transmembrane channel for protons. In ATP synthase. b D. . CuB is a component. E. All of the following are properties of ATP synthase EXCEPT: A. E. All are true for F1 unit of ATP synthase EXCEPT: A. mobile coenzyme Q collecting electrons. The model of electron transport includes all EXCEPT: A. energy-driven conformational changes convert O-sites to L-sites. Ser. cyt a.37. rotenone is not strong enough to inhibit all of the electron transport chain. B. c. b. Ser. cyt a3 . hemoglobin C. Cyanide and azide bind tightly to the ferric form of ____. myoglobin. therefore. ATP synthesis. C. Yes. complex IV E. Arg. catalytic cooperativity between subunits. Can not be determined from the information given. complex I B. there is not an electron source. E. electron. hemoglobin E. c. proton C. g. and carbon monoxide toxicity arises from its affinity for the iron of ____. complex II C. Asp. proton E. there is still a source of electrons from Complex II. none. B. nucleotide B. binding of substrates. The hypothesis for proton driven ATP synthesis depends on ____ neutralization of the negative charge on c-subunit ____ residues as the rotor turns causing the ____-subunit to turn relative to the three ____-subunit ____ binding sites of F1. b. D. A. Does electron transport stop if rotenone is added? Why? A. conformational change in the b-subunits releasing ATP. cyt a3. rotenone B. cyt c. complex III D. b. cyt a3 B. nucleotide 39. nucleotide D. C. proton. it is an uncoupler 40. E. proton. hemoglobin. g. g. (ab)3 complex rotates relative to a fixed b-subunit. D. 41. Characteristics of proton gradient driven enzyme conformational change in ATP synthase include all EXCEPT: A. g. 38. No. oligomycin C. rotenone inhibits complex III. antimycin D. electrons can not be passed on. proton. A. Which complex will be affected if rotenone is added? A. b. cyanide E. Yes. hemoglobin D. No. Asp. all of the above 42. Which of the following is an inhibitor of Complex IV? A. electron. changing the conformation of each in sequence. . All of the following are part of apoptosis EXCEPT: A. E. adipocytes E. Obesin. C. 44. ratio of atoms of phosphorous to oxygen in phosphate (P i). D. the mitochondrial outer membrane protein-permeable pores close.43. D. E. ____ creates a passive proton channel through which protons flow from the cytosol to the mitochondrial matrix in ____. Electron transport continues and ATP synthesis continues. Electron transport continues. D. All are properties of uncouplers EXCEPT: A. molecules of phosphate released from ATP per oxygen utilized by muscle tissue. 45. Electron transport speeds up and ATP synthesis stops. What percentage of the proton gradient energy to synthesize and transport ATP to the cytosol is involved in the ATP-ADP transport? A. 10% B. E. Electron transport stops and ATP synthesis stops. C. microorganisms B. They dissipate the proton gradient. B. Thermogenin (UCP1). Oligomycin. Electron transport stops and ATP synthesis continues. caspases are activated. 15% C. B. brown adipose tissue C. C.4-dinitrophenol to respiring mitochondria? A. none of the above 46. What is the effect of adding oligomycin and then 2. Pi uptake per oxygen atom by mitochondria. B. a series of proteolytic reactions. Heat is produced. Nothing. 47. ATP/ADP ratio increases. none of the above. none of the above 48. Demerol. C. cytochrome c is released. P/O ratio is defined as: A. nerve tissue D. D. 25% D. 50% E. A. the uncoupler and inhibitor cancel each other out. They were briefly used as weight-loss drugs. E. molecules of ATP formed per two electrons flowing through electron transport chain. mitochondrial membrane permeabilization (MMP). B. E. E.49. C. A. NADH C. D. C. D. It shuttles NADH across the mitochondrial membrane to yield 2. B E. E. D. one is located in the cytosol. B. F. phosphate E. C. B. E B. B. dihydroxyacetone phosphate (DHAP) + NADH ® NAD+ + glycerol-3-phosphate. E C. It only operates efficiently when the [NADH] in the cytoplasm is higher than in the matrix. Malate is a key component in the shuttle process. E. The appropriate sequence for the malate-aspartate shuttle is: A. F. it results in the net transfer of electrons to the electron transport chain from NADH in the cytosol. glycerol-3-phosphate reductase. A D. A characteristic of the glycerophosphate shuttle is: A. D. B. works to carry electrons into mitochondria. one is located in the inner mitochondrial membrane. C. glycerol-3-phosphate is translocated across the inner mitochondrial membrane into the matrix. D. C. E. 54. citrate B. A. 51. E. triose phosphate isomerase. C. D. A. DHAP dehydrogenase. E. B. F . glycerol-3-phosphate dehydrogenase. glycerol kinase. It shuttles "NADH electron equivalents" across the mitochondrial membrane to yield 1. B. B. C. C. C. mitochondrial enzyme has bound coenzyme Q. D. The reaction. D. F. there are two distinct forms of glycerol-3-phosphate dehydrogenase in cells with this shuttle. C. F. B. is catalyzed by: A. D. F. All are correct about the glycerophosphate shuttle EXCEPT: A. E. A. 53. one form of glycerol-3-phosphate dehydrogenase is a flavoprotein. Which of the following molecules is LEAST LIKELY to be transported across the inner mitochondrial membrane? A. All are properties of glycerol-3-phosphate dehydrogenases EXCEPT: A. FAD-dependent mitochondrial enzyme.5 ATP/ADH. pyruvate D. OAA transaminated to aspartate OAA reduced to malate Malate oxidized to OAA Malate translocated to matrix Aspartate translocated to cytosol Aspartate transaminated to QAA A. 52. B. Aspartate is a key component in the shuttle process. D. electrons derived from this shuttle enter the electron transport chain at UQ.5 ATP/NADH. malate 50. two malate dehydrogenase enzymes. OAA translocates inner mitochondrial membrane. they do not have to translocate ATP-ADP across the mitochondrial membranes D. they don't have to use shuttles to reoxidize reduced nucleotides C. 56. B. all are true. they use an electron transport chain that translocates more protons E. A. Bacteria and other prokaryotic cells have the capacity to get more ATP/glucose oxidized than eukaryotic cells because ____. reactions are reversible. D. they are simpler and have less going on B.55. so they are more efficient. All are characteristics of the malate-aspartate shuttle EXCEPT: A. electrons of cytosolic NADH are translocated to mitochondrial NADH. none of the above . C. E. . E. monoacylglycerols. F. fatty acids E. B. F. triacylglycerol lipase. A. B. convert the inactive lipase into the active form. B. A. triacylglycerol lipase. all are true. B. D. glycerol. F. glycerol D. A. B. E E. protein kinase activation cAMP production triacylglycerol lipase activation hormone binding receptor adenylyl cyclase activation diacylglycerol lipase and monoacylglycerol lipase activity A. E D. emulsify the triacylglycerol globules to produce greater surface area which will increase the activity of the lipase. E. A. C 3. adipocytes D. D. diacylglycerols. A. glucagon. D. 4. ACTH (adrenocorticotropic hormone). D. insulin. muscles C.Chapter 23--Fatty Acid Catabolism Key 1. epinephrine (adrenaline). The primary storage form of lipid is ____ and it is normally stored in the ____. fatty acids B. phospholipid. activate the cleavage at the C-2 position. adipocytes E. fatty acids . C. are coenzymes for pancreatic lipase. E. liver B. acid lipase. E. B. Bile salts are important in the initial digestion of triacylglycerols in the intestine because they: A. A. F B. permit greater permeability of the triacylglycerols through the intestinal membrane. D. B. fatty acids. triacylglycerols. liver 2. D. A. glycerol C. pancreatic lipase. D. D. E. Fatty acids are mobilized from adipose cells in response to all of the hormones EXCEPT: A. C. The sequence for activation of the release of fatty acids from adipose cells is: A. F. fatty acids. C. C. F. B. C C. C. monoacylglycerol. C. triacylglycerols. cholesterol. The majority of lipid digestion occurs in the duodenum by the enzyme ____ that produces ____ and ____ for absorption. E. 5. pancreatic lipase. D. inner mitochondrial membrane E. C. VLDL. E. cytoplasm C. D. are formed in and secreted by the liver. plasma D. A. it involves the formation of a high energy thioester linkage. The correct sequence for transport of fatty acyl groups from the cytosol to the matrix is: A. E. intestinal B. B. B. none of the above 9. an acyl-adenylate intermediate is formed. 8. ____ carries long-chain fatty acyl groups across the ____ membrane.6. lymphatic E. D. inner mitochondrial E. D. hydrolysis of ATP produces AMP and PPi. TPP. A. chylomicron. D. lymphatic B. E B. B. All are correct concerning the activation of a fatty acid to an acyl-CoA EXCEPT: A. C. E. B. outer mitochondrial 11. lymphatic 7. C. B. D. carnitine acyltransferase I tranaslocase of carnitine and O-acylcarnitine carnitine acyltransferase II fatty acyl-CoA synthesis O-acylcarnitine fatty acyl-CoA in matrix A. A. D. A. triacylglycerols. Absorbed lipids are condensed with glycerol in the epithelial cells into ____ and re-packaged into ____ that are initially transported by the ____ system. E. VLDL. C C. F E. triacylglycerols. outer mitochondrial membrane D. C. triacylglycerols. D. with further hydrolysis of PPi to drive the reaction. Chylomicrons: A. activation is accompanied by the hydrolysis of ATP to ADP and P i. are formed in adipose tissue. Biotin. Where in the cell are fatty acids condensed with coenzyme A to form acyl-CoA for b-oxidation? A. F D. A. VLDL. E. B. are primary energy sources for the brain. B. 10. F. F. all are correct. portal D. LDL. E. plasma C. phospholipids. Carnitine. C. transport dietary triacylglycerols through the bloodstream. CoA-SH. E. contain more phospholipid than triacylglycerol molecules. F. F . C. mitochondrial matrix B. C. triacylglycerols. A. B. portal C. A. Carnitine. B. ligases E. a-ketoglutarate dehydrogenase E. For the complete oxidation of a saturated fatty acid with 16 carbons. Enoyl-CoA hydratase belongs to what class of enzymes? A. E. oxaloacetate ® citrate ® isocitrate ® a-ketoglutarate D. 15. can be used for all EXCEPT: A. a primary alcohol to an aldehyde. hydrolases C. All are characteristics of acyl-CoA dehydrogenase EXCEPT: A. comes in at least three isozymes each specific for fatty acids of differing chain lengths. E. acyl-CoA dehydrogenase. D. C. how many times must the b-oxidation cycle be repeated? A. malate dehydrogenase 17. b-hydroxyacyl-CoA dehydrogenase. 14. 8 D. E. b-hydroxyacyl-CoA dehydrogenase. synthesis of ketone bodies. B. uses tightly bound FAD. 4 B. synthesis of amino acids. acyl-CoA dehydrogenase. aconitase B. an aldehyde to a carboxylic acid. a-ketoglutarate ® succinyl-CoA ® succinate ® fumarate 13. lyases D. D. 7 C. a carbon-carbon single bond to a carbon-carbon double bond.12. synthesis of glucose. none of the above. oxidoreductases B. A. a secondary alcohol to a ketone. The first oxidation in the b-oxidation of saturated fatty acids is catalyzed by ____ and is the conversion of ____. catabolism in the TCA cycle. isocitrate dehydrogenase D. acetyl-CoA. all are correct. succinate ® fumarate ® malate ® oxaloacetate B. acyl-CoA dehydrogenase. C. an aldehyde to a ketone. C. electrons are transferred to electron transfer flavoprotein (ETF) and on to Q of the electron transport system. The product of b-oxidation. The first three reactions of b-oxidation of saturated fatty acids are analogous to which sequence of metabolic reactions already discussed? A. L-Hydroxyacyl-CoA dehydrogenase is analogous in catalytic activity to what enzyme of the citric acid cycle? A. isocitrate ® a-ketoglutarate ® succinate ® fumarate C. D. transferases 16. B. phosphoenolpyruvate ® pyruvate ® acetyl-CoA ® citrate E. 16 . 18. oxidation of the Ca-Cb bond. 6 E. citrate synthase C. 8 acetyl CoA. 8 NADH. 9 acetyl CoA. cis-D4 double bonds to trans-D3. 28 by TCA plus 7 by b-oxidation E. During b-oxidation of certain unsaturated fatty acids. 7 NADH. 23. trans-D2. 8 NADH. C. 16 C. enoyl-CoA dehydrogenase D. 7 FADH2. even-chain fatty acids. acyl-CoA dehydrogenase B. involved in saturated fatty acid catabolism. vitamin B12-dependent. 9 acetyl CoA. cooperates with b-oxidation in fatty acid oxidation. acyl-CoA isomerase 24. 7 FADH2. cis-D2. D.4-dienoyl-CoA reductase EXCEPT: A. citrate B. all are true. acyl-CoA dehydrogenase C. B. 32 by TCA plus 8 by b-oxidation C. classic B12-enzyme catalyzed rearrangement. succinate E. 1 ATP equivalents D. 7 NADH. A. How many NADH are generated from the complete oxidation of palmitoyl-CoA to CO2? A. odd-chain fatty acids. trans-D2. reduces trans-D2. even-chain fatty acids. succinyl-CoA D. C. 24 by TCA plus 8 by b-oxidation 21. 18 B. 8 acetyl CoA. none are true 22.19. enoyl-CoA dehydrogenase E. uses NADPH. 21 by TCA plus 7 by b-oxidation D. trans-D2. All are true for 2. cis-D3-fatty acyl-CoAs are formed that must be converted to ____-fatty acyl-CoAs by the enzyme ____. 12 D. 8 FADH2. produces succinyl-CoA. E. 7 FADH2. ____. D. 2 ATP equivalents C. E. 1 ATP equivalents . All are true for methylmalonyl-CoA mutase EXCEPT: A. 25. How many NAD+ are reduced in the b-oxidation of stearoyl-CoA to form nine molecules of acetyl-CoA? A. 6 FADH2. trans-D3. odd-chain fatty acids. B. isocitrate C. does hemolytic cleavage of Co3+ -C bond. 1 ATP equivalents B. 8 acetyl CoA. A. all are true. Propionyl-CoA is a product of b-oxidation of ____ and is ultimately converted to the TCA cycle intermediate. 9 NADH. 9 E. 2 ATP equivalents E. 8 20. 24 by TCA plus 7 by b-oxidation B. What are the b-oxidation products of oleic acid (18:1D9) and how many ATP equivalents are required for activation? A. C. mitochondria of liver. B. b-hydroxybutyrate and acetoacetate D. Ketone body carbons enter the major metabolic pathways of the cells by conversion to: A. glucose. acetone. carnitine shuttle. carnitine shuttle. pyruvate dehydrogenase. Which of the following correctly describes the conversion of a fatty acid to CO 2? A. acetoacetate and acetone 28. hydroxyacetone phosphate and butyrate C. D. butyrate and acetyl-CoA B. E. glucose E. fatty acids C. but require insulin to enter target tissues. acetoacetate. but during starvation ____ may be the major source of energy. fatty acids. b-oxidation. The brain normally uses ____ as its source of metabolic energy. Ketone bodies are transported to the tissues of utilization: A. . CAC D. incorporated into VLDLs. butyrate. pyruvate. C. butyrate. B. D. What are the three most common ketone bodies? A. complexed to serum albumin. activation to acyl CoA. 29. citrate. E. D. 32. citrate synthase. D. Ketone bodies are synthesized in the: A. activation to acyl CoA. ketone bodies. all are true 30. b-hydroxybutyrate dehydrogenase. In ketone body biosynthesis. acetoacetate. cytosol of muscle. carnitine shuttle. A. b-oxidation. CAC. acetyl-CoA.26. acetyl-CoA and acetone E. E. freely dissolved in serum. acetone. B. glucose-6-phosphate. endoplasmic reticulum of heart. C. complexed to fatty acid binding protein. aconitase. CAC B. succinyl-CoA synthase. amino acids D. 31. b-oxidation. amino acids. CAC C. carnitine shuttle E. B. activation to acyl CoA. b-oxidation. none of the above. plasma membrane of brain. none of the above are correct 27. E. the HMG-CoA lyase is mechanistically the reverse of the first half of the reaction catalyzed by: A. C. ketone bodies B. activation to acyl CoA. glyceraldehyde-3-phosphate dehydrogenase. Fatty acid synthase (FAS) differs from b-oxidation in all of the following ways EXCEPT: A. OAA. malonate 4. B. Reducing equivalents derived from glycolysis in the form of NADH can be transformed into ____ for fatty acid biosynthesis by the combined actions of ____ and ____. The reaction catalyzed by ____ is: Citrate + ATP +CoA ® acetyl-CoA + ____ + ____. The main source(s) of NADPH for fatty acid biosynthesis is (are): A. butyrate C. malate dehydrogenase . glycolysis. malate dehydrogenase. glyceraldehyde-3-phosphate dehydrogenase. oxidative phosphorylation. NADPH. A. TCA cycle. malic enzyme B. OAA. A. AMP + Pi B. AMP + PPi D. AMP + PPi C. malic enzyme D. 5. so the carbons must be converted to ____ for transport to the cytosol. OAA. an acetal 3. NADPH. citrate synthase. D. B. all are true. uses NADPH for oxidoreductase reactions. an amide D. ATP-citrate lyase. an ester B. C. citrate D. malic enzyme C. There is no transporter for acetyl-CoA to exit the mitochondria. pyruvate E. E. OAA. acyl carrier protein linked intermediates. malate dehydrogenase E. a thioester C. malate dehydrogenase. NADH. an ether E. malate dehydrogenase. the conversion of OAA to malate by malate dehydrogenase. D. NADPH. ATP. citrate synthase. acetone B. E. 2. malate. occurs in cytosol. malic enzyme and the pentose phosphate pathway. ADP + Pi 6. C. A. ADP + Pi E. ATP-citrate lyase.Chapter 24--Lipid Biosynthesis Key 1. What type of linkage occurs between ACP and the intermediates in fatty acid biosynthesis? A. all of the enzymes are on one polypeptide. citrate synthase. 7. biotin carboxylase and transcarboxylase subunits. All are characteristic of acetyl-CoA carboxylase EXCEPT: A. Phosphorylation of regulatory sites on acetyl-CoA carboxylase ____ the affinity for citrate and ____ the affinity for fatty acyl-CoAs requiring ____ levels of fatty acyl-CoAs for inhibition. thiamin. increases. B. D. 12. phosphorylation causes separation of the polymeric form of the enzyme to inactive protomers E. increases. fatty acid synthase. Which of the following statements regarding phosphorylation of acetyl-CoA carboxylase is correct? A. decreases. allosterically stimulated by ATP. pyridoxal phosphate and TPP. pyruvate carboxylase. low D. B. Acetyl-CoA carboxylase in animals is regulated by all of the following EXCEPT: A. acetyl-CoA carboxylase . propionate carboxylase. allosterically inhibited by palmitoyl-CoA. E. none are correct 13. low B. NADH and FAD. all are correct. high E. is catalyzed by: A. ATP-citrate lyase. acetyl-CoA carboxylase. decreases. both b and d are true 11. high [citrate] inhibits the phosphorylated form D. The coenzymes of acetyl-CoA carboxylase are: A. biotin carboxyl carrier protein subunits. D. formation of malonyl-CoA. citrate shifts the enzyme toward the active polymer. high C. decreases. C. C. all are correct. decreases. increases. D. The committed step in fatty acid biosynthesis. phosphorylation is a result of glucagon binding to its receptor C. FAD and Q. biotin and ATP. B. allosteric inhibition by palmitoyl-CoA. Acyl carrier protein has the same ____ group as the "business end" of ____. E. 9. 10. E. A. biotin. phosphorylation by protein kinase A. A. allosterically stimulated by citrate. 8. TPP and folic acid. D. B. C. TPP B. phosphorylation causes activation only in the presence of palmitoyl-CoA B. C. E. increases. palmitoleoyl-ACP E. All are characteristic of fatty acid elongation EXCEPT: A.C. E B. C 16. b-ketoacyl-ACP synthase (KSase). B. A. acetyl-CoA additions. E. 15. b-hydroxydecanoyl-ACP is dehydrated by b-hydroxydecanoyl thioester dehydrase to form a double bond ____ to the thioester in the ____ configuration which is further elongated to form ____. B. B. b. palmitoyl-ACP . E. B. vitamin B6 E. acetyl-CoA carboxylase. B. A. E. cis. palmitoyl-ACP B. A. D. trans. D. C. The formation of acetoacetyl-ACP is catalyzed by: A. D. pyridoxal phosphate. trans. phosphopantetheine. the correct sequence of enzyme catalyzed reactions are: A.b. In E. C. involves cytochrome b5 reductase. palmitoleoyl-ACP C. D. C.g. B. cAMP D. uses CoA rather than ACP. A C. C. b-ketoacyl-ACP synthase b-ketoacyl reductase b-hydroxyacyl dehydratase enoyl reductase acetyl transferase A. uses both NADH and NADPH. C. b. CoA 14. Stearoyl-CoA desaturase has all of the following characteristics EXCEPT: A. E D. A. E. cis. B. D. C. acetyl transacylase. D. E.g. E.g. b-hydroxyacyl dehydratase. E. B. a. occurs in the endoplasmic reticulum. 17. In fatty acid synthase. involves cytochrome b5. produces a trans double bond. a. C. C. D. requires ATP and biotin. NADH and O2 are required. A. 18. occurs in cytosol and endoplasmic reticulum. B. b-ketoacyl reductase. phosphoadenosine. b. D E. palmitoleoyl-ACP D. coli.b. D. cis. activation. NADPH: inhibits 23. citrate stimulates acetyl-CoA carboxylase. Insulin promotes the ____ of acetyl-CoA carboxylase and ____ of triacylglycerol lipase by ____ the phosphodiesterases that converts cAMP to AMP. inactivation. Which enzyme is NOT USED to catalyze reactions in the synthesis of phosphatidic acid from these two precursors? A. inactivation. C. inhibiting E. glucagon: activates C. B. methyl C. activation. E. D.19. it can be synthesized from linoleic acid in mammals. acyl-CoAs are inhibitors of acetyl-CoA carboxylase. A. acyldihydroxyacetone-P reductase D. insulin receptor binding maintains acetyl-CoA carboxylase in the inactive form. saturated. citrate: activates E. phosphatidylethanolamine. . plants can introduce double bonds into fatty acids between D 9 and the ____-end of the chain. Regulation of fatty acid synthesis in humans is affected by all of the following EXCEPT: A. glycerol kinase B. methyl. cardiolipins. Both glycerol and dihydroxyacetone phosphate can serve as precursors for phosphatidic acid. triose phosphate isomerase C. saturated. glucagon promotes phosphorylation and inactivation of acetyl-CoA carboxylase. carboxyl. D. phosphatidylinositol. E. activation. stimulating B. malonyl-CoA binding to carnitine acyltransferase inhibits available substrate for b-oxidation. carboxyl. inhibiting D. it contains five cis-double bonds. C. stimulating C. carboxyl. E. carboxyl 20. mono-unsaturated. E. inactivation. 1-acylglycerol-3-phosphate acyltransferase 25. while mammals can only introduce double bonds between D 9 and the ____-end of the chain. Which of the following is correctly paired with its effect upon fatty acid synthesis? A. phosphatidyl glycerol. it is an omega-6 fatty acid. polyunsaturated. B. methyl B. B. all are true. C. CDP-diacylglycerols are precursors for the synthesis of all EXCEPT: A. inactivation. carboxyl E. methyl. A. palmitoyl CoA: activates B. coli does NOT have any ____ fatty acids. none are true 24. All of the following are characteristics of arachidonic acid EXCEPT: A. D. methyl D. polyunsaturated. 21. glycerol-3-phosphate acyltransferase E. it is a precursor of leukotrienes and most prostaglandins. 22. all are correct. activation. insulin: inhibits D. Components for plasmalogen biosynthesis include all EXCEPT: A. Eicosanoids. long-chain alcohol. glycerophospholipids C. A. none of the above. A lipid that does NOT have a sphingosine backbone is: A. diacylglycerols. arachidonate and glycine. Platelet-activating factor displays dramatic ability to ____ blood vessels and thus ____ blood pressure. Arachadonates. E. palmitate and glycerol. ganglioside GM1. NADPH. D. ____ are all derived from 20-carbon fatty acids that are acylated to membrane phospholipids and released by the enzyme ____. fatty alcohol and dihydroxyacetone phosphate (DHAP). B. phospholipase A2 E. 1-OH D. E. A. Sphinganine is acylated in the ____-position. glycerophospholipids D. phospholipase A1 D. CDP-diacylglycerols. CDP-ethanolamine. dilate. C. phosphatidic acid is converted directly either to ____ or to ____ from which all other ____ are derived. triacylglycerols. A. 3-OH B. all are true 31. ceramide. D. Arachadonates. triacylglycerol lipase B. The carbons of sphinganine are derived from: A. C. 2-NH2 C. monoacylglycerols. A.26. NADH and O2. acylglycerols. phospholipase A2 . fatty acyl-CoA. In eukaryotes. Arachadonates. and to aggregate platelets. B. phospholipase A1 C. phosphatidylinositol. constrict. B. sphingomyelin. dilate. acylglycerols 27. 3-NH2 E. monoacylglycerols. acylglycerols B. 28. constrict. phospholipids. glycerophospholipids E. Eicosanoids. reduce B. cerebroside. diacylglycerols. phospholipids. increase D. E. reduce C. 30. C. 32. palmitate and serine. increase 29. glycerol. CDP-diacylglycerols. D. B. All are characteristics of COX-2 inhibitors EXCEPT: A. E. B B. All are characteristics of eicosanoids EXCEPT: A. B. The committed step in cholesterol biosynthesis is catalyzed by: A. A. 34. tissue injury E. 38. include prostaglandins. An important mechanism of arachidonate release and eicosanoid synthesis involves ____ and ____. of cholesterol synthesis is: A. E. D D. B. less renal toxicity than COX-1 inhibitors. high blood sugar B. C. C. D. heart. low blood sugar D. C. low blood sugar C. D. A. glucagon release. HMG-CoA synthase. E. The PRIMARY site. intestine. C. insulin release. selectively block inflammation mediated by COX-2. D. C. squalene monooxygenase. usually act very near their site of synthesis. are NSAIDs. D. D. HMG-CoA lyase. it inhibits the activity of prostaglandin endoperoxide synthase (COX). C. The correct sequence for synthesis of mevalonate from acetyl-CoA is: A. 37. 36. E. B. but not the only site. C E. D. E C. all are true 35. all are correct. HMG-CoA reductase. B. C. D. D 39. D. it stimulates ring opening in prostaglandin synthesis. liver. exert their effects at very low concentrations. tissue injury. A. C. B. C. A. B. HMG-CoA synthase formation of 3-hydroxy-3-methylglutaryl-CoA b-ketothiolase catalyzed condensation HMG-CoA reductase activity Formation of acetoacetyl-CoA A. . less potential for stomach lesions than aspirin. it is classed as a non-steroidal anti-inflammatory drug (NSAID). mevalonate kinase. adipose. B. A. E. E. muscle. All are true for aspirin EXCEPT: A. C. inflammation. B. all are true.33. E. D. it does not affect the peroxidase activity of prostaglandin endoperoxide synthase (COX). A. E. E. derived from arachidonic acid. thromboxanes and leukotrienes. B. E. it acetylates the serine in the active site of the cyclooxygenase (COX). D. B. C. C. The "statins" are a series of drugs used to: A. B. E. E. high [cholesterol] increases half-life for HMG-CoA reductase. C. E. B E. E. E. bound to the endoplasmic reticulum (ER). C. A. B. D. C D. uses FAD and NADPH. D. A. D. Order the lipoproteins from lowest density to highest density. derivatives of cholesterol used to lower cholesterol levels. D. C. B. C. B D. C. E. B. E 42. chylomicrons HDL IDL VLDL LDL A. C. low [cholesterol] increases mRNA for HMG-CoA reductase. D. D. A. D. A. none are true. D. E. C. Characteristics of squalene monooxygenase include all EXCEPT: A. A. C. The appropriate sequence of intermediates between mevalonate and squalene are: A. phosphorylation by cAMP cascade inactivates HMG-CoA reductase. C. C. C B. requires a soluble protein activator. E. D.40. C. phosphatases activate HMG-CoA reductase. inhibit fatty acid synthesis in diet drugs. B. A C. B. B. B. B. derivatives or mimics of mevinolin used to inhibit HMG-CoA reductase. A. B. A E. D. B. E. E. 43. D. 41. high [cholesterol] results in lower mRNA for HMG-CoA reductase. D C. requires O2. E B. E. A. D. 44. D. E. A. A. B . All are regulatory mechanisms of HMG-CoA reductase EXCEPT: A. all are true. widely prescribed drugs used to inhibit squalene monooxygenase. geranyl pyrophosphate isopentenyl pyrophosphate 5-phosphomevalonate farnesyl pyrophosphate dimethylallyl pyrophosphate A. E. cholesterol esters. triacylglycerols. phospholipids 49. HDL. cholesterol C. lipoprotein lipase C. proteins.45. made by the liver and utilized in the intestine. All are correct for bile salts EXCEPT: A. D. insert well into membranes because they are strictly nonpolar. C. A. life span of 5 to 6 days. proteins. Which of the following lipoproteins is INCORRECTLY defined? A. C. HDL receptors 52. high HDLs correlates with high risk of cardiovascular disease. triacylglycerols. 48. newly formed is cholesterol ester free. C. The general genetic defect responsible for ____ is the absence or dysfunction of ____ in the body such that blood cholesterol levels are typically 300 to over 800 mg/dL. cholesterol esters. phospholipids. The major circulatory complex for cholesterol and cholesterol esters ("bad cholesterol") is the: A. triacylglycerol lipase B. chylomicron: transport of dietary lipids to the liver B. E. phospholipids. LDL. triacylglycerols. cholesterol B. cholesterol esters. 51. cholesterol esters. D. LDL particles D. HDL C. hypercholesterolemia. triacylglycerols. into which is inserted ____ and ____. A. chylomicrons. A. returns cholesterol and cholesterol esters to liver. chylomicrons B. phospholipids. chylomicrons E. triacylglycerols. triacylglycerols E. LDL particles C. Lipoproteins consist of a core of ____ and ____ surrounded by a single layer of ____. VLDL. proteins. proteins. cholesterol esters. cholesterol. HDL: scavenger of extra-hepatic cholesterol C. Lipoprotein lipase hydrolyzes ____ from VLDL particles to convert the VLDL into ____. B. conjugates of bile acids with glycine and taurine. LDL: transport of cholesterol to extra-hepatic tissue D. LCAT. hypocholesterolemia. cholesterol esters. . triacylglycerols. E. highly effective as detergents. LDL receptors E. accumulates cholesterol esters via LCAT action. cholesterol. cholesterol esters. A. D. cholesterol D. derived from cholesterol. IDL D. phospholipids. familial hypercholesterolemia. all of the above are correct 47. LDL receptors D. HDL particles B. LDL 46. VLDL: transport of triacylglycerols from the liver E. E. VLDL E. familial hypocholesterolemia. IDL. Dietary lipids are "packaged" in the intestine into ____ for transport in the blood stream. proteins. triacylglycerols. B. HDL particles 50. Characteristics of HDLs include all EXCEPT: A. B. steroid 5a-reductase D. stimulates gluconeogenesis and glycogen synthesis in liver. D. usually involve cytochrome P-450. D. B. lactate dehydrogenase C. ____ is an intermediate on the biosynthetic pathway from cholesterol to both male and female hormones. Properties of progesterone include all EXCEPT: A. 59.53. often catalyze hydroxylation reactions on ring-systems such as sterols. C. Progesterone C. Which of the following is correctly paired with its precursor? A. A. produced from pregnenolone in ER. all are true. C. Male baldness. Characteristics of mixed-function oxidases include all EXCEPT: A. E. B. produces cholic acid. 56. arachidonic acid ® prostaglandins C. D. its substrate is cholesterol. E. all are true. one product is CO2. utilizes cytochrome P-450. found in mitochondria of adrenal glands. stanozolol. prepares the uterus for attachment of a fertilized ovum. testosterone ® progesterone D. Cortisol D. glucocorticoids. dihydrotestosterone. cholesterol ® palmitic acid B. C. secreted from corpus luteum in late menstrual cycle. 57. C. Testosterone 55. none of the above 58. none of the above . has two hydroxylase activities. D. E. 54. B. aldosterone ® cholic acid E. synthesis in the adrenal cortex activated by ACTH. cholesterol. E. inhibits allergic and inflammatory responses. inhibits protein synthesis and stimulates protein degradation in muscle. Estradiol E. exerts an immunosuppressive effect and an inhibition of wound healing. All are true for the action of cortisol EXCEPT: A. all are correct. use both NADPH and O2. prostate hyperplasia and prostate cancer have been implicated in elevated levels of ____ and treatment involves inhibition of ____. gluconeogenesis B. A. B. All are characteristics of desmolase EXCEPT: A. mevinolin E. Aldosterone B. Chapter 22 Metabolic Interrelationships Multiple Choice 1. are obtained by synthesis in mitochondria. are converted to ketones. Ans: E 3. tyrosine. D. glucose and pyruvate B. B. The major metabolites transported by blood to connect these pathways are A. oxidative decarboxylation of a-ketoglutarate to succinyl CoA C. oxidative decarboxylation of isocitrate to α-ketoglutarate B. During anaerobic exercise. are minor energy sources. E. are usually converted to triglycerides. D. cysteine. palmitate and glycerol Ans: D 2. During heavy exercise. tryptophan. B. C. During a period of fasting. leucine. Ans: D . E. conversion of pyruvate to lactic acid Ans: E 4. glucose and alanine D. C. conversion of succinate to fumarate E. provide the energy for most ATP synthesis. alanine and lactate C. muscle will derive the most energy from the catabolism of A. Long-chain fatty acids in heart A. the Cori Cycle employs the gluconeogenic pathway in the liver and the glycolytic pathway in muscle. oxidative decarboxylation of pyruvate to acetyl CoA D. glucose and lactate E. lysine. which reaction would be most active in the exercising muscle? A. glycogenolysis E. is potentially gluconeogenic. amidation of glutamate from the blood by liver. increased production of dihydroxyacetone phosphate from glycerol phosphate Ans: A . and its point of entry into the gluconeogenic pathway is as triose phosphate. C. amidation of glutamate released from muscle protein. is potentially gluconeogenic. E.5. C. increased conversion of beta-hydroxybutyrate to acetoacetate C. is ketogenic because it is derived from the catabolism of triacylglycerols. Which reaction does NOT occur in muscle? A. oxidation of leucine by adipose. increased reduction of pyruvate B. D. Ans: D 7. cannot support the net synthesis of glucose. synthesis of glucose from alanine B. because glycerol cannot be phosphorylated in vivo. formation of glutamine from glutamate Ans: A 6. oxidation of lactic acid D. and its point of entry into the gluconeogenic pathway is as pyruvate. Free glycerol A. oxidation of isoleucine and valine released from muscle protein. Ans: B 8. is not a gluconeogenic substrate and is readily excreted in the urine. oxidation of beta-hydroxybutyric acid C. B. increased production of oxaloacetate from malate E. B. What change from normal is likely to result from the ingestion of ethanol? A. E. D. and skeletal muscle. heart. The major source of glutamine in blood during short term fasting is A. decreased ketogenesis due to lack of acetyl-CoA D. amino acid breakdown in brain and other tissues. some of the transaminases. Partial uncoupling of oxidative phosphorylation Ans: D 11. pyruvate dehydrogenase Ans: C 10. ATP-citrate lyase B. B. There would be a transient period of negative nitrogen balance followed by nitrogen equilibrium. fatty acid synthase D. Abnormally large rise in glucose consumption when oxygen is admitted to an anaerobic incubation of tissue B. UDP-glucose and galactose. Urea excretion would increase above that in the pre-diet period because protein synthesis could not continue. glucokinase. E. D. The rate of synthesis of phenylalanine would decrease compared to that in the prediet period. D. glycerol kinase. Large increase in the pyruvate:lactate ratio following exercise D. C.9. acetyl-CoA carboxylase. phosphofructokinase. Insulin induces the hepatic synthesis of A. E. The person would be in nitrogen equilibrium. Which statement regarding this individual is true? A. glucose 1-phosphate + galactose 6-phosphate. hormone sensitive lipase. pyruvate kinase. glucose 6-phosphatase. The person would be in negative nitrogen balance. UDP-galactose + fructose. isocitric dehydrogenase C. Direct precursors of lactose are A. C. Which of the following is most consistent with a defective malate-aspartate shuttle A. phosphorylase. Diminished ability of mitochondria to oxidize isocitrate C. PEP carboxykinase E. Ans: D . Abnormally large decrease in intracellular pH of muscle during exercise E. B. A normal adult is placed on a diet containing adequate amounts of all essential nutrients but no tyrosine. UDP-galactose + glucose Ans: E 12. glucose 6-phosphatase. UDP-glucose and fructose. phosphofructokinase and pyruvate kinase. Fasted state. C. There is not enough insulin to promote lipid synthesis Ans: D 16. The decrease in lipoproteins prevents transport of ketone bodies D. rate of glycogen breakdown in the liver. skeletal or heart muscle. C. E. Ketone bodies are not needed for the brain in this case C. Working muscle oxidizes fatty acids to lactate. 0-2 hours after refeeding Ans: B 17. level of cAMP in adipose tissue. Monomers of a starchy meal. not followed by vigorous exercise end up as glycogen in liver. An amino acid which is ketogenic but not glucogenic A. B. None of the other answers is correct. 2-3 hours postprandial B. B. C. D. Ans: C 15. E. B. The central control points in glycolysis are hexokinase. uptake of glucose by adipose tissue. Well-fed state. . 12-36 hours postprandial D. It takes 2 days of starvation before ketone bodies are synthesized B. Resting liver only minimally oxidizes lactate. D. uptake of glucose by the liver. Early fasted state. Why do type II diabetics generally not develop ketoacidosis? A. Early refed state. When is hepatic glycogenolysis a primary source of blood glucose? A. can provide carbons for the synthesis of fatty acids. uptake of glucose by erythrocytes. There is enough residual insulin to suppress lipolysis E. 3-12 hours postprandial C. All of the following are true EXCEPT which one? A.13. Initially insulin increases the A. Ans: D 14. E. cannot be oxidized through the Krebs cycle. can provide carbons for the net synthesis of glucose. D. Resting muscle produces negligible lactic acid. can enter the Krebs cycle at the level of oxaloacetate. glucose 1-phosphate and galactose E. lactic acid D. He has set the treadmill to a fast pace and has begun to run. citric acid C. which are the immediate precursors for the formation of lactose? A. A. non-protein derived energy sources. D. UDP-galactose and glucose B. creatinine. B. galactose 1-phosphate and glucose D.e. by the incomplete combustion of 2-carbon molecules derived from adipose stores. increased by epinephrine D. UDP-glucose and galactose . decreased by testosterone Ans: C 21.. A 25 year old. increased by insulin E. by neutralizing metabolic by-products such as urea. by synthesizing essential amino acids to meet the body demands. galactose and glucose C.Ans: C 18. for the metabolic needs of the brain and nervous system. decreased by cortisol B. healthy male has begun a treadmill exercise program. the body makes a major adaptation to conserve its protein stores A. As his physical activity continues for several minutes his heart rate would be expected to increase and the levels of _______________ would be expected to rise significantly in his blood. Blood glucose levels are A. uric acid Ans: C 19. i. aspartic acid B. by utilization of ketone bodies. In starvation. In the lactating mammary gland. Ans: C 20. C. decreased by glucagon C. pyruvic acid E. heteropolysaccharides. liver D. blood glucose levels are maintained by gluconeogenesis. brain E. insulin affects each of the following EXCEPT which one? A. The carbons utilized for glucose synthesis under these circumstances are derived primarily from A. Transport of glucose into cells D. nucleic acid. healthy individual. Glycogen breakdown in which of the following tissues can be used to support blood glucose levels during periods of fasting? A. protein. Lipogenesis from acetyl-CoA B. spleen Ans: C 23. C. Oxidation of fatty acids E. Rate of glycolysis C. glycogen. Ans: E 24. Which of the following reactions gives the greatest yield of high energy phosphate? A. In the liver. Gluconeogenesis Ans: C . E.Ans: A 22. skeletal muscle B. fatty acids. D. B. During periods of prolonged fasting in a normal. glucose --> 2 pyruvate D. 2 pyruvate --> 2 acetyl-CoA + 2 carbon dioxide E. palmitoyl-CoA --> 8 acetyl-CoA B. 8 acetyl-CoA --> 16 carbon dioxide C. 2 lactate --> 2 pyruvate Ans: B 25. adipose tissue C. Erythrocyte pyruvate kinase E. Hormone-sensitive lipase is decreased in activity. Ans: E 30.6-bisphosphatase C. Phosphorylase B. alpha-ketoglutarate dehydrogenase complex. Exercise intolerance would be MOST likely to accompany a deficiency of A. E. ADP. B. It is utilized as an energy source by cardiac muscles. phosphorylase b. Fructose-l . It is oxidized to carbon dioxide and water in skeletal muscles. which enzyme in liver cells is most likely to decrease in amount? A. C. isocitrate dehydrogenase. Ans: D 28. D. glucose-6-phosphate phosphatase E. In the transition from a well-fed to a fasting state. citrate synthase. B. C. It is converted to glucose in the liver. It diffuses out of the muscle cell into the surrounding interstitial fluid. Serum circulating ketone bodies are increased in amounts. acetyl-CoA carboxylase C. All of the following statements concerning the fate of lactate produced by skeletal muscle during strenuous exercise are true EXCEPT which one? A. Glucokinase D. Muscle glucose-6-phosphatase Ans: A 29.26. D. PEP carboxykinase B. D. Which of the following is/are expected to occur during and immediately following the absorption of a meal? A. Mitochondrial concentrations of oxaloacetate are depressed. glycogen phosphorylase Ans: B 27. or ATP) EXCEPT A. The activity of each of the following enzymes or enzyme complexes is regulated by the concentration of the adenine nucleotides (AMP. pyruvate carboxylase D. . B. phosphofructokinase. E. C. Lipoprotein lipase is decreased in amounts. Acetyl-CoA carboxylase is inhibited by the presence of increased amounts of citrate in the cytosol. C. Ans: C 34. glycogen phosphorylase a Ans: D 33. asparagine B. C. The Cori Cycle. B. aspartate D. ornithine E. phosphofructokinase. growing children. glycerol phosphate dehydrogenase Ans: D 35. hormone-sensitive lipase C. Adipose tissue contains little or none of which one of the following enzymes? A. A positive nitrogen balance would be expected in all of the following conditions EXCEPT A. glucose 6-phosphatase. glycerol kinase E. . restoring the energy balance between liver and muscle.Ans: C 31. glucose --> 2 lactate + 2ATP (Muscle) and 2 lactate + 6 ATP --> glucose (Liver). glucose 6-phosphate dehydrogenase B. glyceraldehyde 3-phosphate dehydrogenase D. The enzyme that is termed the glucose sensor of the liver is A. D. is important because A. consumption of a diet with increased protein. glucose 6-phosphate dehydrogenase. glutamine C. pregnancy. B. there is a net destruction of ATP. D. Which amino acid is most important as a non-toxic form in which ammonia is transported in the bloodstream? A. glutamate Ans: B 32. recovery from trauma or surgery. B. it results in the net generation of glucose in the liver and ATP in the muscles without the build up of high lactate levels. C. it enables muscle mass to be used for energy in conditions of extreme starvation. D. it serves to prevent lactate levels from dropping too low in the blood, which would impair brain function. E. it enables glucose 6-phosphate to be transported across the liver cell plasma membrane. Ans: B 36. Glucagon plays a homeostatic role by A. being released from the pancreas in response to elevated blood glucose levels and then activating the liver phosphorylase system. B. being released from the pancreas in response to lowered blood glucose levels and then activating the liver phosphorylase system. C. stimulating the release of glucose residues from muscle glycogen during periods of intense muscular activity. D. activating adenylate cyclase in skeletal muscle cells. E. facilitating glucose uptake into skeletal muscle. Ans: B 37. In skeletal muscle during strenuous exercise, the NADH produced in the reaction catalyzed by glyceraldehyde 3- phosphate dehydrogenase is reoxidized primarily by A. malate dehydrogenase. B. lactate dehydrogenase. C. pyruvate dehydrogenase. D. isocitrate dehydrogenase. E. glucose 6-phosphate dehydrogenase. Ans: B 38. The most direct point of entry for alanine into the gluconeogenic pathway is as A. oxaloacetate. B. pyruvate. C. glyceraldehyde 3-phosphate. D. dihydroxyacetone phosphate. E. 2-ketobutyrate. Ans: B 39. Oxidation of fatty acids in liver mitochondria may facilitate gluconeogenesis by A. B. C. D. E. supporting the phosphorylation of ADP. forming acetyl CoA which can contribute to the net synthesis of glucose. reducing FAD and NADP+. transporting carnitine into mitochondria. decreasing the dependence of phosphorylation of ADP on oxygen consumption. Ans: A 40. How does a lack of oxygen most directly cause a decrease in the activity of the Krebs cycle? A. The synthesis of lactate from pyruvate is inhibited. B. High levels of malonyl CoA inhibit carnitine acyl transferase I. C. Electron transport is interrupted. D. Circulating levels of epinephrine are increased. E. The rate of glycogenolysis decreases. Ans: C 41. In untreated insulin-dependent diabetes, all these differences from the normal state are observed EXCEPT A. transport of glucose into adipose tissue is increased. B. gluconeogenesis is increased. C. glycogen breakdown in liver is increased. D. lipolysis in adipose tissue is increased. E. ketogenesis is increased. Ans: A 42. Why do tumors tend to use glycolysis as the source of most of their ATP? A. Angiogenesis delivers a large amount of glucose B. Lack of oxygen induces HIF-1a C. These cells have fewer mitochondria D. These cells do not have enzymes of electron transport E. These cells do not have TCA enzymes Ans: B 43. The mature erythrocyte A. uses fatty acids as the main source of energy. B. reduces NADP+ to NADPH largely through the hexose monophosphate shunt. C. produces bisphosphoglycerate (DPG) largely via the hexose monophosphate shunt. D. synthesizes proteins. E. contains relatively extensive endoplasmic reticulum. Ans: B 44. Which of the following statements about catabolism of body proteins during starvation is correct? A. The breakdown of proteins occurs spontaneously, without the need for enzyme catalysis. B. The amino acids resulting from protein breakdown are either reused as such or are deaminated and their carbon skeletons used as a source of energy. C. The first amino acids to be catabolized are derived from the protein storage depot in liver. D. The amino acids derived are used primarily for synthesis of fatty acids. E. The initial steps in the process involve cleavage of the amino acid side chains from polypeptides. Ans: B 45. During exercise epinephrine and glucagon levels are elevated and insulin levels are depressed. Under these conditions, which enzyme should be activated? A. glycogen synthase B. fatty acid synthase C. hormone-sensitive lipase D. acetyl CoA carboxylase E. ATP-citrate lyase Ans: C 46. In the long term fasting state, a large proportion of the energy of the brain is derived from circulating A. acetoacetyl-CoA. B. acetone. C. beta-hydroxybutyrate. D. oxalacetate. E. malonic acid. Ans: C 47. What determines that the metabolism of amino acids in the liver is low during the well-fed state? A. Amino acids are not absorbed from the diet B. Amino acids are not removed from portal blood flow C. Endogenous inhibitors are synthesized D. The liver participates in the Cori Cycle E. The necessary catabolic enzymes have high Kms Ans: E 48. The substrate normally utilized as the major source of energy by the brain is A. B. C. D. E. triglycerides. fatty acids. ketone bodies. amino acids. glucose. Ans: E 49. Certain amino acids can increase the concentration of blood glucose because A. they can be oxidized via the Krebs cycle. B. they are essential. C. their carbon chains can be converted to intermediates in the Krebs cycle. D. their carbon chains can be converted to acetyl-CoA. E. they can undergo transamination reactions. Ans: C 50. The enzyme in muscle which is most directly stimulated by epinephrine is A. glycogen synthase. B. phosphofructokinase. C. isocitrate dehydrogenase. D. glucose-6-phosphatase. E. adenylate cyclase. Ans: E 51. Which reaction in the liver should be stimulated most in a starving individual? A. serine dehydratase reaction B. pyruvate dehydrogenase reaction C. acetyl CoA carboxylase reaction D. citrate lyase reaction E. conversion of oxaloacetate to aspartate Ans: A 52. The major source of energy in the heart of a runner who has just won a 1, 000 meter race would be A. glycogen. B. phospholipids. C. plasma glucose. D. plasma amino acids. E. plasma fatty acids. Ans: E 53. Which amino acid is not taken up well by liver, and must be supplied by its essential amino acid precursor? A. Arginine B. Cysteine C. Glycine D. Serine E. Tyrosine Ans: B 54. The largest amount of glycogen in humans is stored in A. skeletal muscle. B. liver. C. brain. D. adipose tissue. E. heart muscle. Ans: A 55. The principal source of NH4+ for glutamine synthesis in muscle is A. glutamate. B. adenosine. C. inosine. D. urea. E. carbamoyl phosphate. Ans: B 56. Nitrogen is carried from skeletal muscle to the liver in the post-absorptive state primarily in the form of 1. arginine 2. glutamine 3. alanine 4 . Serine 5 . histidine A. 1 and 3 B. 2 and 4 C. 1 and 4 D. 2 and 3 E. 3 and 4 Ans: D 57. The brain utilizes ketone bodies rather than fatty acids because A. ketone bodies are a more efficient fuel. B. brain tissue cannot metabolize fatty acids to any significant degree. C. ketone bodies can be converted into glucose. D. none of the above. Ans: B 58. The liver normally uses which one of the following for its own energy needs in the fed state? A. Free fatty acids B. Amino acids C. glucose D. Glycerol Ans: B 59. Lactate production during muscular contraction is ascribed in part to A. an overproduction of acetyl-CoA not metabolized in the Krebs cycle. B. an underproduction of acetyl-CoA for utilization in the Krebs cycle. C. temporary anaerobic state in muscle. D. overabundance of ATP produced by metabolism through the Krebs cycle. Ans: C 60. The principal store of metabolic energy available during long term fasting or starvation is A. muscle glycogen. B. liver glycogen. C. muscle protein. D. adipose tissue triacylglycerol. Ans: D 61. Physiological conditions that promote the synthesis of ketone bodies also promote the A. oxidation of fatty acids in erythrocytes. B. oxidation of glucose in adipose tissue. C. synthesis of amino acids in skeletal muscle. D. synthesis of fatty acids in cardiac muscle. E. synthesis of glucose in liver. Ans: E 62. What is the main source of carbon atoms for ketone bodies in a diabetic? A. heart B. liver C. brain D. adipose E. skeletal muscle C. Proline D. Increased levels of ATP in the fed state helps to channel acetyl CoA into fat synthesis by inhibiting . increased rates of protein synthesis. hyperglycemia (high blood glucose) B. Ans: C 64. adipose tissue D. Which of the following tissues would have the highest levels of gluconeogenesis during starvation? A. brain B. B. when three meals are eaten. an increased rate of glycogenolysis. normal blood sugar levels C. hypoglycemia (low blood glucose) E. Leucine Ans: B 66.Ans: D 63. In an uncontrolled diabetic which of the following amino acids would yield both glucose and ketone bodies? A. increased activity of pyruvate carboxylase. increased gluconeogenesis Ans: D 67. muscle Ans: D 65. Which of the following would you expect to see in a fasting patient who was deficient in glucose -6-phosphatase? A. E. increased release of glucose by the liver D. Tyrosine C. Glycine E. Alanine B. liver E. Compared to metabolic activity during the daytime. red blood cells C. increased activity of phosphoenolpyruvate carboxykinase. D. decreased activity of acetyl-CoA carboxylase. an overnight fast should cause all of the following EXCEPT A. an inhibition of phosphofructokinase. isocitrate dehydrogenase. B. rapid glycolysis. to phosphorylate glycogen. Ans: B 68. E. rapid gluconeogenesis. D. glucose synthesis from fatty acids during glucose deprivation . Ans: A 69. B. an increase in glycogen synthesis. to phosphorylate fructose 6-phosphate. increased rate of gluconeogenesis from pyruvate C. C. B. directly in contraction. Increased activity of PEP carboxykinase E. C. D. E. Elevated NADH/NAD+ ratio D. D. phosphocreatine is used A. acetyl CoA carboxylase.A. citrate lyase. ypoglycemia associated with ethanol intoxication is accompanied by: A. a shut down of the TCA cycle. E. activation of pyruvate dehydrogenase B. Decreased lactate/pyruvate ratio B. Elevated blood pyruvate C. increased activity of alpha-ketoglutarate dehydrogenase Ans: C 70. ketosis may develop as a result of which of the circumstances below? A. citrate synthase. increased concentration of lactate in plasma D. During contraction. palmitate thiokinase (CoA synthase). An increased concentration of intracellular AMP in skeletal muscle would cause A. Ans: B 71. What change from normal will accompany the ingestion of sufficient ethanol to make an individual drunk? A. to phosphorylate ADP. Increased activity of pyruvate carboxylase Ans: C 72. C. to activate phosphofructokinase. decreased ratio of NADH/NAD+ in liver E. muscle and kidney. acute attack of gout carnitine transferase I deficiency hyperglycemia fat mobilization to support gluconeogenesis Ans: E 73. It inhibits glycolysis at the step catalyzed by phosphofructokinase. It may be used in the Krebs cycle for production of energy. The glucose-alanine cycle functions chiefly in the exchange of carbon and nitrogen between A. It is a source of acetyl-CoA for fatty acid synthesis. Ans: D 75. D. It activates the pyruvate dehydrogenase complex. The reversible transfer of the acetyl group to acyl carrier protein (ACP) to form acetyl-ACP. D. E. Ans: B 76. E. B. liver and muscle.B. C. B. C. starvation or low carbohydrate diet. muscle and brain. nutrient storage and protein anabolism. Ans: C . mobilization of nutrients and protein catabolism. D. Which statement regarding citrate in mammalian metabolism is FALSE? A. Condensation with glyoxylate to form malate and free CoA in plants. It activates fatty acid synthesis. Ans: B 74. kidney and liver. B. A high insulin to glucagon ratio indicates A. E. Condensation with acetoacetyl-CoA to form beta-hydroxy-beta-methyl glutaryl-CoA. C. B. Acetyl-CoA has been found to undergo all of the following reactions EXCEPT which one? A. gut and liver. E. The ATP dependent fixation of carbon dioxide to form malonyl-CoA. the effects of severe infection. C. D. D. The NAD dependent fixation of carbon dioxide to form pyruvate and free CoA. C. produced from glycogen in skeletal muscle. fatty acid synthase. aerobic metabolism. Free glucose. D. B.3-diphosphoglycerate. Ans: E 78. aldolase. 3'. lipoprotein lipase. phosphorylase. B. E. B. Lactate from muscle is used in the liver as a gluconeogenic substrate. fructose B. glycerol . phosphoglucomutase. D. C. Which statement about the Cori cycle is TRUE? A. C. It is the cycle in the liver by which glycogen is synthesized from and degraded to glucose 1-phosphate. B. The major pathway by which mature adult red cells generate ATP is A. C. Which of the following is the major substrate used for energy by resting muscle? A. anaerobic glycolysis. C. D. hexose monophosphate shunt activity. insulin stimulates the activity of each of the following proteins EXCEPT A. All of the component reactions occur in skeletal muscle. In the metabolism of adipose triacylglycerols. Ans: D 81. nonesterified fatty acids C. glucose transporter 4. hexokinase. glucose 6-phosphatase. is utilized for the synthesis of glycogen in the liver. All of the component reactions occur in the liver.5'-AMP phosphodiesterase. lipid peroxidation. generation of 2. Ans: B 79. Blood glucose levels can not be increased by muscle glycogen degradation because muscle lacks A. E. E. E.77. D. hormone-sensitive lipase. Ans: B 80. Ketone bodies D. glycolysis. decreased energy supply to the liver and hepatic cell death B. lactate Ans: B 82. B. The liver accomplishes this by a process called A. Ans: D 86. depletion of glycogen stores in liver E. hypoglycemia one or two hours after a meal Ans: E 84. B. Ketone bodies are synthesized in A. C. C. glycogenesis. If glucose-6-phosphatase were deficient in liver. glycogenolysis. D. During periods of strenuous exercise the major energy source for cardiac muscle is A. E. muscle glycogen. lipolysis. liver glycogen. gluconeogenesis. E. D. muscle for utilization in brain and liver. . triacylglycerol. beta-hydroxybutyrate E. protein. The largest reserve of potential metabolic energy in humans is found in the form of A. what would best characterize the expected change in metabolism relative to the normal state? A. brain for utilization in liver. glucose B. C. liver for utilization in muscle. Free fatty acids C. decreased rate of ketogenesis D. The blood glucose level in an individual who is fasting is maintained at a relativel y constant level by the liver. free glucose.D. B. Ans: D 85. hyperglycemia after a normal meal C. Lactate Ans: A 83. The following compounds are potential substrates (carbon sources) for the gluconeogenic pathway EXCEPT which one? A. glutamic acid B. succinic acid E. thyroid hormones. somatomedin A. Integration of metabolism between organs occurs primarily through: A. The increase in blood sugar level resulting from epinephrine injection can best be explained by which one of the following? A. Which one of the following would you not expect in liver during an overnight fast? A. epinephrine. Induction/repression D. E. C. cortisol. Hormones C. Ans: C 87. glucagon. Gluconeogenesis Ans: D 88. Substrate supply Ans: B 91. Absorption of carbohydrate from the digestive tract C. oleic acid D. increasing rate of glycogenolysis . E.D. liver for utilization in liver. Covalent modification E. Liver glycogenesis D. Synthesis of carbohydrate from fat B. Ans: B 89. Liver glycogenolysis E. D. brain for utilization in brain. Allosteric effectors B. The effects of insulin on glucose uptake by muscle tissue are most directly opposed by A. citrate Ans: C 90. B. aspartic acid C. C. All of the following compounds are essential in the diet EXCEPT A. C. pyruvate carboxylase. C. stearic acid. increasing rates of protein synthesis increasing activity of pyruvate carboxylase decreasing activity of acetyl CoA carboxylase increasing activity of phosphoenolpyruvate carboxykinase Ans: B 92. nicotinic acid. The enzyme activity that changes LEAST when a well-fed animal undergoes a two day fast is A. In the brain. During starvation. linoleic acid. hexokinase D. aldolase. D. ornithine E. which of the following amino acids can be transaminated to directly provide pyruvate for gluconeogenesis? A. aspartic acid Ans: B . phosphofructokinase Ans: C 95. valine B. phosphofructokinase. Ans: C 94.B. glucokinase C. potassium. the reaction ATP + glucose ----> glucose-6-phosphate is catalyzed by A. Ans: B 93. phosphohexose isomerase B. hormone-sensitive lipase. D. phosphoglucomutase E. glutamate D. B. E. D. acetyl CoA carboxylase. glycine B. alanine C. E. E. epinephrine D. D.catabolism of tyrosine E.96. hormone-sensitive lipase B.fatty acid biosynthesis Ans: A 98. pyruvate carboxylase . isocitrate dehydrogenase . citrate lyase. Gluconeogenesis C. Amino acid synthesis B. plasma albumin C. citrate. ethanol and carbon dioxide. D. E.gluconeogenesis B. Which enzyme does NOT catalyze a committed step in the indicated metabolic pathway? A. What process does line IV in the diagram above depict in glucose homeostasis? A.Krebs cycle C. the levels of epinephrine and glucagon rise and the level of insulin falls.glycolysis D. Ans: C 99. C. tyrosine aminotransferase . The mobilization of fatty acids from adipose tissue during stress would require the involvement of all but which of the following? A. phosphofructokinase . B. B. apolipoprotein C II E. E. During exercise. Glycogenolysis D. cAMP Ans: D 97. acetyl CoA carboxylase. glycogen synthase. pyruvate. During vigorous exercise. Lipolysis Ans: B 100. Ketone body formation E. lipoprotein lipase. leading to activation of A. lactate. glucose. acetyl CoA carboxylase . muscles will increase secretion of A. phosphorylase. C. . Ans: B .