CGS NS 201 Lecture Notes - Lecture 4: Woolly Mammoth, Irish Elk, Cave Bear
9 Aug 2018
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Earliest evidence of life on earth: fossils. First evidence of eukaryotic life 2. 1 bya. Endosymbiont theory: argues that mitochondria, plastids and possibly other organelles of eukaryotic cells, originate through symbiosis b/w multiple microorganisms. Some cells lose the rigid cell wall. Anaerobic, predatory prokaryotic cell engulfs an aerobic bacterium, than descendants of engulfed bacterium evolve into mitochondria, the mitochondria containing cell engulfs a photosynthetic bacterium. Mitochondria, chloroplasts, flagellum: evidence to support it: Mitochondria is about the size of a modern bacteria. Mitochondrial ribosomes are similar in size & structure to modern bacterial ribosomes. How did photosynthesis change earth: it requires sunlight, carbon dioxide and hydrogen, first source: hydrogen sulfide gas, second source: water, (hydrogen source) water +co2 sugar + o2. Caused larger cells to engulf smaller cells. What was earth like during the cretaceous period: 250 mya. Land reptiles move back to the sea. Developed webbed feet and flippers: 82 mya. Two major types of dinosaurs: sauropods and thuropods.
