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McGill University
Biology (Sci)
BIOL 111

Bio 111 Alanna Houston September 11, 2007 BACTERIA - Know the main cell structures and their differences between prokaryotes and eukaryotes - Unique cell wall – sugars linked by weird amino acids. - Membranes – lipid bilayer - 3 challenges: o Energy transformation (more variety) o Reproduction (DNA replicates and then cell splits, plasmids for DNA exchange) o Response to environment - endospores (essentially inactive - anthrax, botulism), chemotaxis (swim towards high concentration, chemical gradient, and move with flagella) - 10 30individual bacteria on earth - Bacterial classification: (in textbook) o Traditional  Shape – coccus, bacilli, strepto, spirochete  Cell wall – gram stain shows purple (if purple, peptidoglycan about 5x thicknd, if not purple there is a thin peptidoglycan and 2 outer lipid membrane) o More modern classification is based on DNA sequencing  Species – DNA different enough  Relationships based on DNA similarity - phylogeny - If we wanted to eliminate all bacteria: o Unlike virus, bacteria have unique features to attack →  Antibiotics (creation of peptidoglycan – penicillin,  Smaller (70S) ribosome – erythromycin, tetracyclines,  Folic acid synthesis (bacteria make their own, animals get from diet) – sulfa drugs. o Bacteria can acquire resistance very easily! - Prokaryotes live in: o The earth (air, water, soil) o Humans (intestines, skin, mouth, not in blood brain urine or lungs) o In other organisms (plant roots, cow rumens, aphids making protein) Bio 111 Alanna Houston o In factories (making yoghurt/cheese/sauerkraut, eating oil spills) o Extreme environments (120 degrees C, extreme salt, extreme metal toxicity) - Prokaryotes consist of Bacteria and Archea - Archea are largely extremophiles (extreme salt, temperature, methane) and are only recognized as a distinct group since the 1970’s Bacteria Archea Eukaryotes Peptidoglycan Yes No No Nucleus/Organelles No No Yes Membrane Lipids Normal Unusual Normal Ribosomes 70S 80S 80S - Penicillin works against the peptidoglycan layer therefore penicillin cannot work against archea (archea do not have a peptidoglycan layer) - Volta found methane gas at the bottom of the lake (bacteria produce methane) ( burned with a blue flame) - EATING: o An oxidation-reduction reaction releases energy (transfer an electron from an atom holding it loosely to one that
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