BIOL 1104 Lecture Notes - Lecture 6: Plastid, Cyanobacteria, Cytoskeleton
20 Apr 2020
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Prokaryotes thrive almost everywhere, including places too acidic, salty, cold or hot for most other organisms. Prokaryotes were earth"s sole inhabitant from 3. 5 to about 2. 1 billion years ago and dramatically changed its atmosphere. The oxygen revolution occurred between 2. 7 to 2. 3 billion years ago. The initial rise on o2 was likely caused by ancient cyanobacteria. Later increases in atmospheric o2 might have caused eukaryotic cells containing chloroplasts. It"s argued that the first mass extinction may have been caused by oxygen and its increase which killed the organisms that don"t rely or use oxygen. Animals, plants, fungi, and protists belong to the domain eukarya. Mitochondria and plastids (chloroplasts and related organelles) were formerly prokaryotes living within larger host cells. Serial endosymbiosis proposes that mitochondria evolved before the plastids through a sequence of endosymbiotic events. Mitochondria evolved by endosymbiosis of an aerobic prokaryote. Plastids evolved later by endosymbiosis of a photosynthetic. Evidence for the endosymbiotic origin of mitochondria and plastids include:
