Prokaryotic EukaryoticSIMILARITIES PLANT ANIMAL Cytoplasm Ribosomes Cell Wall Plasma Cell Membrane Nucleus Nucleolus Nuclear Pore Nuclear Double Membrane Rough Endoplasmic Reticulum Smooth Endoplasmic Reticulum Golgi Apparatus Lysosome Mitochondrion Cytoskeleton DIFFERENCES Mesosome In-folded Membrane Chloroplast Centriole + Centrosome Slime Capsule (maybe) Vacuole Small Large Medium Pilli Plasmid Flagellum (maybe) Flagella (maybe) Nucleotide - contains circular DNA Glycogen granules DIFFERENCES PROKARYOTIC EUKARYOTIC No nucleus Nucleus No membrane-bound organelles Membrane-bound organelles Has cell wall Cell wall only in plant DNA is free in cytoplasm DNA enclosed in nucleus Small cell Large cell Always unicellular Often multicellular DNA is circular, without proteins – not in chromosome form DNA as loop DNA is linear, and associated with proteins DNA as strands Small ribosomes Large ribosomes Asexual reproduction Asexual or sexual reproduction Cell division by binary fission Cell division by mitosis or meiosis No cytoskeleton Has a cytoskeleton No nuclear double membrane (because no membrane-bound organelles) Has nuclear double membrane EUKARYOTIC Organelle Structure Function Nucleus Largest organelle Nuclear envelope is a double membrane Nuclear pores make the membrane porous Contains DNA Contains dense nucleolus where ribosomes are made Site of mRNA synthesis Ribosomes Found in the cytoplasm, either free or attached to rER. Made of rRNA and proteins Has binding sites for mRNA + tRNA Site of protein synthesis rER Interconnected flattened membrane- bound sacs (cisternae) with ribosomes attached (this is why it feels rough). Involved in protein transport to other parts of the cell Folds and processes proteins made at the ribosomes sER Interconnected flattened tubular membrane-bound sacs (cisternae) without ribosomes attached (this is why it feels smooth) Contains enzymes for metabolic functions Synthesizes and processes lipids + steroids Synthesizes, stores and processes carbohydrates Makes reproductive hormones Mitochondria Contains a double membrane – the inner membrane is folded into cristae (finger- like projections) which provides a large surface area for enzymes to attach Matric (jelly) in the middle – contains the enzymes needed for respiration as well as DNA loop and ribosomes Site of later stages of anaerobic respiration Golgi Apparatus Stack of membrane-bound sacs enclosed by a membrane Formed from fused vesicles from the ER Site of protein folding and packaging Receives and modifies proteins from rER, then packages the modified proteins into vesicles to be transported thus making lysosomes. Produces secretory enzymes. Lysosome Round organelle surrounded by a double membrane Contains digestive enzymes Releases enzymes outside the cell Can be used to digest invading cells – protects against bacterial attack Removes cell debris by breaking down old cells Vesicle Small fluid sac surrounded by a double membrane Found in the cytoplasm Transports substances in and out of the cell Formed at the Golgi Apparatus, ER or surface membrane. Cell surface membrane Made of phospholipids and proteins Partially permeable bilayer membrane Controls movement of substances in and out of cells Receptor molecules allow it to respond to chemicals Separates cell contents from outside Involved in cell recognition and signaling Holds channel proteins and carriers Cytoplasm Jelly-like substance Contains organelles in eukaryotic cells Contains enzymes needed for metabolic reactions in prokaryotic cells Centriole Hollow cylinders arranged at right angles to each other Only one pair found in animal cells Made of protein microtubules Involved in spindle formation Involved in cellular transport Electron micrographs show the ultrastructure (fine structure) of these two cells. Protein Transport 1. DNA contains instructions to make proteins 2. DNA is transcribed to form mRNA strand 3. mRNA leaves nucleus via the porous nuclear membrane 4. mRNA attached to ribosomes on the rER 5. mRNA is translated and produces a polypeptide chain; the ribosome reads the instructions and use a code to assemble a protein o Signal Recognition Particle attaches to a signal peptide o S-R-P binds with the receptor protein o Receptor protein aids with the transfer of the polypeptide chain through to the rER membrane o Once the polypeptide chain (protein) passes into the rER the signal peptide detaches – it can be reused, 6. The protein folds shape into its secondary and tertiary form, as it is being moved along through the rER 7. The protein is pinched off and packaged into a vesicle at the end of the rER. 8. A vesicle forms when the rER membrane closes around the protein. 9. Vesicle containing the protein is transported to the Golgi Apparatus, where it fuses with one end and releases the protein 10.The protein in modified as it passes through the GA 11.Again, the modified protein is packaged into vesicles and pinched off. They are now called lysosomes OR they can be packaged into large secretory vesicles, which go to the cell membrane for exocytosis – this allows extracellular enzymes to be released outside of the cell. Cellular Organization Cell – can be unspecialized or specialized to carry out a specific function e.g. muscle, nerve Tissues – groups of specialized cells working together to carry out a specific function Organ – groups of different tissues working together to carry out a specific function e.g. leaf, heart Organ system – groups of organs working together to carry out a specific life function e.g. circulatory system How are cells organized into tissues? Cell Cycle (MITOSIS) Mitosis – a process of nuclear division where two genetically identical cells are formed from one parent cell Mitosis is a type of cell division of somatic cells, which retains the full (diploid) number of chromosomes [2n]. In humans, cells with 46 chromosomes divide to form to identical daughter cells, both with 46 chromosomes also. Role and importance: To make genetically identical cells For growth of multicellular organisms For asexual reproduction (binary fission – no gametes required) To replace cells To repair damaged cells STAGES INTERPHASE