Transcript First Life Notes and PPT

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.