Bio January 25

Bio January 25 - Bio January 25 January 24 contd. o Permian...

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Bio January 25 January 24 cont’d… o Permian extinction – POWERFUL effect on evolution o Cretaceous extinction – thought to be caused by impact of large meteor Iridium ‘spike’ – find thin layer of iridium; iridium is rare, found in outer space Led to rise of mammals PROKARYOTES Features – no membrane-enclosed organelles or nucleus; cell wall; move with flagella or pili Pili also allow conjugation (bacterial sex) Adaptation o Exponential population growth Binary fission (asexual) 1-3 hours! o Endospores (resistant stages) Survive for centuries o Horizontal gene transfer Plasmids (conjugation) pass them back and forth Peptidoglycan formation (penicillin) Ribosomes (erythromycin, tetracycline) Anabaena spp. o N-fixing cyanobacterium Cooperation! Anaerobic (N2 fixation) Aerobic (photosynthesis) Light and CO2 = Photoautotroph Inorganic Chemicals and CO2 = Chemoautotroph Light and Organic compounds = Photoheterotroph
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Bio January 25 - Bio January 25 January 24 contd. o Permian...

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