CAS BI 107 Lecture Notes - Lecture 11: Extinction Event, Biogeography, Prokaryote
4 Nov 2016
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Mass extinction at end of period (96% of species lost) Life"s history and earth history are inextricably linked. Much of life"s history is shaped by events in earth"s history. Early bacteria were photosynthetic, but most used hydrogen (h2s) that did not release oxygen when metabolized. Clade of bacteria photosynthetic (light for energy and h2s for source of protons in photosynthesis) Proteobacteria + h2s: oxygen is released into atmosphere, we owe oxygen atmosphere to cyanobacteria!, no complex animal life would exist if it weren"t for cyanobacteria, had genes that decreased damage free oxygen would cause. Proteins that bind oxygen in complex (resist bad effects of oxygen: origin for aerobic respiration!, horizontal gene transfer (one species transfers genes to another) All photosynthetic organisms that use water got genes from cyanobacteria either through horizontal gene transfer or through incorporation into another cell in eukaryotes - endosymbiotic hypothesis.
