The origins of life on the earth

abundant adenine alanine amino acids ammonia ammonium amounts aqueous solution aspartic acid biochemical biological carbon Chem chemical concentration condensation contain COOH cyanamide cyanoacetylene cyanogen cytosine decomposition dust cloud electric discharge energy enzyme equilibrium evolution evolved example formaldehyde formation formed gases genetic geological glutamic acid glycine half-life hydrogen cyanide hydrolysis hydrolyzed important inorganic isomers L. E. Orgel living organisms lysine material mechanism membranes metabolism meteorites methane mixture molecules nitrogen nucleic acids nucleosides obtained occur OH OH optically active organic compounds origin oxidation oxygen pathways peptide phosphate phosphorylation photochemical photosynthesis planets poly polymerization polymers polynucleotides polypeptides possible prebiotic conditions prebiotic synthesis Precambrian present primitive atmosphere primitive earth primitive ocean purines pyrimidines reaction replication rocks S. L. Miller S. W. Fox Science sequence solar system stars structure sugars surface t-RNA temperature tetramer thermal ultraviolet light uridine volcanoes yield