BIOL 2002 Chapter Notes - Chapter 22: Cyanobacteria, Radiometric Dating, Reducing Atmosphere
Document Summary
Populations of organisms evolve from one generation to the next. All species are related by an evolutionary history. Stage 1: organic molecules formed prior to the existence of cells. Nucleotides and amino acids arose spontaneously under conditions of early earth. Termed prebiotic synthesis - primordial soup (accumulation of molecules) Hypothesis 1 - reducing atmosphere of water vapor, hydrogen gas, methane and ammonia allowed formation of organic molecules. Extraterrestrial hypothesis - meteorites carried organic molecules to earth (carbonaceous chondrites); controversy about heat of meteorites would kill molecules. Deep sea vent hypothesis - superheated water rich in metal ions + hydrogen sulfide mix with cold sea water, organic molecules form in the temperature gradient. Stage 2: organic polymers may have formed on the surface of clay. More complex polymers = dna, rna, proteins. Many clay materials are known to bind organic molecules. 30-60 monomers needed to make a genetic system.
