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lecture 10 (10-) - Prokaryotes and Origin of Life Chapter...

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Prokaryotes and Origin of Life - Chapter 21 I. Origin of Life A) Chemical Evolution 1. comes from hypothesis that life developed from non-living matter 2. four requirements: a) little or no free oxygen i. oxygen oxidizer breaks bonds ii. atmosphere was very low in free oxygen, meaning it was strongly reducing and it was always making bonds b) source of Energy i. thunderstorms ii. volcanic activity iii. meteorites iv. radiation c) presence of chemical building blocks i. water ii. dissolved inorganic minerals in the form of ions iii. CO2, H20 vapor, CO, H2, N2 in atmosphere iv. NH3, H2S, CH4 also in atmosphere d) need time i. earth is about 4.6 billion years old ii. life arose about 3.5 billion years ago B) how did earth go from lifeless to life? 1. started when small organic molecules formed spontaneously 2. these small molecules combined and formed organic macromolecules 3. those combined to form more complex structures 4. those structures were then eventually able to metabolize and reproduce C) formation of small organic molecules 1. pre-biotic soup hypothesis a) oparin-holdane hypothesis b) proposed by Oparin (biochemist) and J.B.S. Holdane (geneticist) c) proposed back in 1920s 2. hypothesis suggests that life formed near the earth’s surface 3. condition at earth’s surface favored the spontaneous formation of simple organic molecules D) Test 1. Miller and Urey – 1950s 2. closed apparatus 3. simulated conditions of early Earth a) H20, CH4, NH3, H2 b) electrical sparks – Energy Figure 21-2 c) examined contents – amino acids and organic molecules d) repeats of the experiment e) all nucleic acid bases of DNA & RNA f) all amino acids, lipids and sugars g) if you add Phosphate group, it forms ATP h)
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