Patrick: An Introduction to Medicinal Chemistry 5eChapter 19: Multiple choice questions and answers Instructions Answer the following questions and then press 'Submit' to get your score. Question 1 Which of the following statements is untrue? a) A bacterial cell is prokaryotic whereas an animal cell is eukaryotic. b) A bacterial cell has a cell wall whereas an animal cell does not. c) Bacterial and animal cells both have a well-defined nucleus. d) Bacteria may contain enzymes that are not present in animal cells. Question 2 Which of the following is the general mechanism of action for erythromycin? a) Inhibition of a metabolic enzyme b) Inhibition of cell wall synthesis c) Disruption of protein synthesis d) Inhibition of nucleic acid transcription and replication Question 3 The following general structure is representative of sulphonamides. Which of the following statements is true for active sulphonamides? a) R1 can be H or an alkyl group b) It is active over a wide range of bacterial species. b) R2 must be hydrogen c) The aromatic ring is essential d) The sulphonamide functional group can be replaced with an ester Question 4 Which of the following statements is true regarding the properties of benzylpenicillin? a) It is a bacteriostatic agent. c) It is resistant to β-lactamases. d) Certain individuals may have an allergic response to it. Question 5 What crucial feature of a penicillin is involved in its mechanism of action? a) Carboxylic acid b) β-lactam ring c) Acyl side chain d) Thiazolidine ring Question 6 What reaction is catalysed by a β-lactamase enzyme? a) The final cross-linking reaction to form the bacterial cell wall b) The hydrolysis of the acyl side chain from penicillin structures c) The hydrolysis of the four-membered ring present in penicillins d) The biosynthesis of the penicillin structure from the amino acids valine and cysteine . Which of the following statements is true regarding the above structure? a) There is no electron withdrawing group on the side chain. and so it is acid sensitive. aureus.Question 7 The following structure (methicillin) was an important penicillin that was introduced in the 1960s to counter the threat of penicillin-resistant strains of S. Question 8 Which of the following statements is accurate in explaining why Gram negative bacteria are generally more resistant to penicillins than Gram positive bacteria? a) Gram negative bacteria have a thicker cell wall b) Gram negative bacteria have an outer hydrophilic membrane that acts as an extra barrier c) Gram negative bacteria can concentrate β-lactamase enzymes in the periplasmic space . d) It has a broader spectrum of activity compared to penicillin G. b) It can be taken orally. c) It is more active than penicillin G. Which of the following statements is true for the methyl substituent at position 3? . d) Gram negative bacteria produce smaller quantities of transpeptidase enzyme Question 9 What role does the acetoxy group at the 3-position of cephalosporins have in enhancing antibacterial activity? a) It acts as a steric shield and masks enzymatic attack at the β-lactam ring. c) It takes part in a transesterification reaction with the carboxylic acid group at position 4. Question 10 The following structure (cefalexin) is a first generation cephalosporin. d) It increases the reactivity of the β-lactam ring by neighbouring group participation. b) It acts as a good leaving group when the β-lactam ring is opened. a) It is a good leaving group b) It is generally good for activity c) It is good for oral activity d) It acts as a steric shield Question 11 What is the target for clavulanic acid? a) The transpeptidase enzyme b) L-ala racemase c) β-lactamase d) Penicillin acylase Question 12 Which of the following antibiotics is a macrolide? a) Chloramphenicol b) Doxycycline c) Erythromycin d) Streptomycin Question 13 Which of the following antibiotics is a tetracycline? a) Chloramphenicol . To which group of compounds does the structure belong? a) Aminoacridines b) Aminoglycosides c) Fluoroquinolones d) Tetracyclines . b) Doxycycline c) Erythromycin d) Streptomycin Question 14 Which of the following antibiotics is responsible for Gray Baby Syndrome? a) Chloramphenicol b) Doxycycline c) Erythromycin d) Streptomycin Question 15 The following structure is a synthetic antibacterial agent. b) There is a binding region which interacts ionically with the α-nitrogen of histamine and results in agonist activity. Which of the following statements is incorrect? a) There is a binding region for the imidazole ring of histamine analogues which is common for agonists and antagonists. Question 1 To what extent are the three nitrogens of histamine ionised at blood pH? a) all three nitrogens are fully ionised b) all three nitrogens are not ionised at all c) the side chain nitrogen is fully ionised and the heterocyclic nitrogens are not ionised d) the side chain nitrogen and one of the heterocyclic nitrogens are fully ionised Question 2 Three binding regions were proposed to be present in the binding site of the H2 receptor.Patrick: An Introduction to Medicinal Chemistry 5e Chapter 25: Multiple choice questions and answers Instructions Answer the following questions and then press 'Submit' to get your score. . What strategy was used in developing burimamide from SK&F 91581? a) extension b) chain extension c) substituent variation d) isosteric replacement Question 4 The following structures show some of the important molecules leading to the discovery of burimamide (B). c) There is a binding region further away from the imidazole ring that produces an antagonist effect if occupied. . Question 3 The following structures show some of the important molecules leading to the discovery of burimamide (B). d) The α-nitrogen of histamine can only bind to the agonist binding region while the guanyl group of Nα- guanylhistamine can only bind to the antagonist binding region. Which of the following statements concerning burimamide is untrue? a) it established the existence of H2-receptors b) it was a good antagonist at H2 receptors with only weak partial agonist activity c) it inhibited gastric acid release from parietal cells d) it indicated that binding to the antagonist binding region involved hydrogen bonding and not ionic bonding Question 5 The following diagram shows development of H2- antagonists from burimamide (structure B). What effect did this change have? a) it introduced an extra binding interaction . A sulphur atom was inserted into the side chain of structure C. b) it stabilised the molecule c) it increased the percentage population of the active heterocyclic tautomer d) it prevented ionisation of the terminal functional group Question 6 The following diagram shows development of H2- antagonists from burimamide (structure B). What was the rationale for the introduction of the coloured methyl group? . a) to block metabolism at that region of the heterocyclic ring b) to introduce a group which would be metabolised in a predictable fashion c) to introduce an electron withdrawing group on the heterocyclic ring to reduce the chance of ionisation d) to introduce an electron donating group on the heterocyclic ring to favour the active tautomer Question 7 The following diagram shows development of H2- antagonists from burimamide (structure B). . b) To replace an unnatural functional group with a naturally occurring group in order to reduce side effects.Why was the thiourea functional group in structure D changed to a guanidine group in structure E? a) To introduce a basic group which could ionise and allow ionic interactions with the binding region. Question 8 The following diagram shows development of H2- antagonists from burimamide (structure B). d) To change the geometry and stereochemistry of the functional group such that it fitted the binding region more closely. . c) To increase the number of hydrogen bond donors present to acquire extra binding interactions. c) It is an electron donating group and decreases the basicity of the functional group such that it does not become protonated and remains un-ionised.Why was the cyanide group introduced into structure F (cimetidine)? a) It is an electron donating group and increases the basicity of the functional group such that it protonates and becomes ionised. d) It is an electron withdrawing group and decreases the basicity of the functional group such that it does not become protonated and remains un-ionised. Question 9 Two regions of cimetidine are susceptible to metabolism. b) It is an electron withdrawing group and increases the basicity of the functional group such that it protonates and becomes ionised. Which regions? a) A and B b) A and C c) B and D d) A and D . Question 10 The following diagram shows various conformations for the cyanoguanidine group of cimetidine. It established that there was only one hydrogen bonding interaction with the receptor in this region. the proton pump inhibitors bind to exposed amino acids in the proton pump. Two of these conformations were found to be disfavoured. Question 11 Once activated. No conclusions could be drawn. c) EE and ZZ. b) EZ and ZZ. Which amino acid is involved? a) serine b) cysteine c) lysine d) histidine Question 12 . It established that there were two hydrogen bonding interactions to different groups within the same binding region. Which ones and what was the implication of this for receptor binding? a) EZ and ZE. d) EE and ZE. It proved the chelation theory of hydrogen bonding. Which arrow is incorrect? a) A b) B c) C d) D Question 13 Omeprazole is an important proton pump inhibitor. Which region is prone to metabolism? a) A .The following mechanism shows how proton pump inhibitors are activated. b) B c) C d) D Question 14 Which microorganism has been associated with the appearance of ulcers? a) Eschericia coli b) Staphylococcus aureus c) Enterococcus faecalis d) Helicobacter pylori Question 15 What bacterial enzyme aids the survival of Helicobacter pylori in the stomach? a) carbonic anhydrase b) β-lactamase c) urease d) transpeptidase .