PCS 182 Lecture Notes - Lecture 10: Unicellular Organism, Great Oxygenation Event, Deuterium
27 Jul 2017
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Early atmosphere: earth formed from the accretion of planetesimals = small solar systems bodies containing, rock, metals. Ices: trapped gases, whi(cid:272)h (cid:449)ere/are trapped i(cid:374) earth"s i(cid:374)terior, volcanoes , expelled interior trapped materials = outgassing. The oxygen catastrophe: these outgassed chemicals were utilized by early anaerobic ( absence of oxygen, microscopic life forms, u(cid:374)til . about 2. 4 billion years ago, organisms use: Photosynthesis: carbon dioxide, water and the energy of sunlight to make carbohydrates (=sugar, starches, fibers, which creates food, and release oxygen as a by-product, for example: 6co2 + 6h2o+ light energy c6h12+6o2 (glucose+ free o2 ) Cyanobacteria: usually blue-green unicellular microbes, prokaryotic (no cell nucleus, found in marine and fresh water, contain chlorophyll, perfor(cid:373)ed photos(cid:455)(cid:374)thesis . A(cid:374)d . : generated significant amounts of free oxygen, which was toxic to the earlier anaerobic life, cyanobacteria secrete a sticky film of mucus; sediment in water covers/ sticks to.
