2/28/12 • What is a halophile? • Key Term: archaea 3/1/12 • What compound makes up the cell wall of a bacterium? • Key terms: same as yesterday Prokaryotes • Domain Bacteria • Domain Archaebacteria Domain Bacteria Domain Archaea 2007-2008 Common ancestor Domain Eukarya Bacteria Structures Bacteria Structures/Functions Structure Function Flagella Tail-like structure for movement Pili Projection of cell wall for sticking to surfaces Cell wall Maintains shape of cell; protects the cell Cell membrane Regulates what leaves and enters the cell DNA Stores hereditary information Ribosomes Builds proetins Prokaryote Structure • Unicellular – bacilli, cocci, spirilli • Size – 1/10 size of eukaryote cell • 1 micron (1um) • Internal structure – no internal compartments • no membrane-bound organelles • only ribosomes – circular, naked DNA • not wrapped around proteins prokaryote cell Genetic variation in bacteria • Mutations – bacteria can reproduce every 20 minutes • binary fission – error rate in copying DNA • 1 in every 200 bacteria has a mutation • Genetic recombination – bacteria swap genes • plasmids – small supplemental circles of DNA Genetic Recombination Type Source of New genes Entry method Transformation DNA in surroundings Endocytosis Transduction Virus w/bacterial DNA Viral mediated entry Conjugation Other bacteria Pili bridge http://www.phschool.com/science/biology_place/labbench/lab6/con cepts1.html http://highered.mcgrawhill.com/sites/0072556781/student_view0/chapter13/animation_quiz_2. html http://www.hhmi.org/biointeractive/animations/conjugation/conj_frames .htm Archaebacteria • Extremophiles: – Thermoacidophiles – love heat (up to 110’C) and acidic environments; require sulfur; anaerobic ex: Sulfolobus, Pyrodictium – Halophiles –love environments with high salt concentrations like the Great Salt Lake and the Dead Sea; nearly all aerobic; all Gram-negative ex: Halococcus – Methanogens – anaerobic methane producers; use carbon dioxide; live in soil, swamps, digestive tracts ex: Methanococcus Bacterial diversity rods and spheres and spirals… Oh My! Prokaryote Cell Wall Structure Gram-positive bacteria peptide side chains cell wall peptidoglycan plasma membrane protein That’s peptidoglycan = polysaccharides + amino acid chains important for lipopolysaccharides = lipids + polysaccharides your doctor to know! outer membrane of Gram-negative bacteria lipopolysaccharides cell wall outer membrane peptidoglycan plasma membrane Bacteria live EVERYWHERE! • Bacteria live in all ecosystems – on plants & animals – in plants & animals – in the soil – in depths of the oceans – in extreme cold – in extreme hot – in extreme salt – on the living – on the dead Prokaryotic metabolism • How do bacteria acquire their energy & nutrients? – photoautotrophs • photosynthetic bacteria – chemoautotrophs • oxidize inorganic compounds – nitrogen, sulfur, hydrogen… – heterotrophs • live on plant & animal matter • decomposers & pathogens Variations in Cell Interior cyanobacterium (photosythetic) bacterium aerobic bacterium Bacteria as pathogens Disease-causing microbes plant diseases wilts, fruit rot, blights animal diseases tooth decay, ulcers anthrax, botulism plague, leprosy, “flesheating” disease STDs: gonorrhea, chlamydia typhoid, cholera TB, pneumonia lyme disease Do you recognize…? Bacteria as beneficial (& necessary) • Life on Earth is dependent on bacteria – decomposers • recycling of nutrients from dead to living – nitrogen fixation • only organisms that can fix N from atmosphere – needed for synthesis of proteins & nucleic acids – plant root nodules – help in digestion (E. coli) • digest cellulose for herbivores – cellulase enzyme • produce vitamins K & B12 for humans – produce foods & medicines • from yogurt to insulin Pathogenic Bacteria Name of bacteria Can you predict the shape from name? Gram-Stain (+ = purple, = pink) Shape Notes
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