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First Life Conditions on Early Earth • CO2, methane and other noxious gases in the atmosphere, extreme heat – Methanogens – Thermophiles • Atmosphere is thick – Sun cannot get through • Oceans are olive green • Caustic and uninhabitable Heavy Bombardment Begins • Oceans are vaporized, toxic rain • Four molecules – Carbon – Nitrogen – Hydrogen – oxygen • Amino acids – Miller-Urey Experiment – Pressure Theory Miller-Urey Experiment • H2O vapor, ammonia, methane, and hydrogen gases • Electric current to simulate lightning • Cooled gases, simulated rain, and collected everything in a flask • Analyzed liquid and found amino acids, sugars, and other organic molecules Pressure Theory • Comets carried amino acids to earth • The pressure of the comet hitting the earth did not cause all organic molecules to break down • Instead, amino acids formed peptides, which can then form proteins Amino Acids • Amino acids form proteins • DNA codes for proteins which allows the functions of the body to be carried out…that fact makes scientists’ think the formation of amino acids/proteins is relevant to the first events that formed life • First life is Archaebacteria, which are extremophilic, like halophiles, methanogens, thermophiles Heavy Bombardment Ceases • The atmosphere begins to clear because there are no longer impacts throwing particles in the air • Microbial life can begin • Life most likely begins in the oceans or hydrothermal vents--protection from the sun – Organisms would be anaerobic – No oxygen available.
