BIS 2B Lecture Notes - Lecture 30: Cellular Respiration, Paleozoic, Extinction Event
3 Dec 2018
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Lecture 30 (look at textbook (24. 1) to track lecture subjects) Hadean, 4. 5-4. 6 billion years ago- life not yet present. Archean, 3. 8 billion years ago- origin of life, prokaryotes flourish. Proterozoic, 2. 5 billion years ago- origin of photosynthesis, multicellular organisms, and eukaryotes. First photosynthetic bacteria- with increasing oxygen in the atmosphere= potential for complex life first eukaryotic cells that have internal organelles and membranes. This is all occurring in the ocean- nothing on land yet (all aquatic organisms). The oxygen revolution: the evolution of life changed the physical nature of earth, which in turn changed the evolution of life . When o 2 it was poisonous to the anaerobic first appeared in the atmosphere, then some evolved the ability to metabolize the o 2 . Advantages: aerobic prokaryotes, but metabolism if faster, more energy is harvest; so aerobes replaced anaerobes in most environments. Paleozoic era : 542-270 mya, lasts nearly 300 million years.
