The Origins of Life on the Earth |
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Page 108
... cytosine , uracil , and thymine - under potentially prebiotic conditions has not been investigated as extensively as purine synthesis . NH2 HN HN CH3 $ 13 H Cytosine N H Uracil N H Thymine A study of the products of the action of an ...
... cytosine , uracil , and thymine - under potentially prebiotic conditions has not been investigated as extensively as purine synthesis . NH2 HN HN CH3 $ 13 H Cytosine N H Uracil N H Thymine A study of the products of the action of an ...
Page 109
... cytosine in almost 100 % yield . We do not know the sequence of steps leading to ( 8 ) , but the following is quite plausible . HC = C - CEN NCO , N CICINIU J - 4-4- CH -NCO CH O = C = N CH H2N CH + CO2 CH CH N H H A second , closely ...
... cytosine in almost 100 % yield . We do not know the sequence of steps leading to ( 8 ) , but the following is quite plausible . HC = C - CEN NCO , N CICINIU J - 4-4- CH -NCO CH O = C = N CH H2N CH + CO2 CH CH N H H A second , closely ...
Page 123
... cytosine is also quite stable . However , cytosine hydrolyzes to uracil rather rapidly , and cytidine is hydrolyzed to uridine at a similar rate ( a half - life less than 20,000 years under reasonable prebiotic conditions ) . This is a ...
... cytosine is also quite stable . However , cytosine hydrolyzes to uracil rather rapidly , and cytidine is hydrolyzed to uridine at a similar rate ( a half - life less than 20,000 years under reasonable prebiotic conditions ) . This is a ...
Contents
PREBIOTIC SYNTHESIS OF PURINES PYRIMIDINES | 8 |
THE COMPOSITION | 12 |
GEOLOGICAL EVIDENCE | 16 |
Copyright | |
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abundant active adenine alanine aldehydes amino acids ammonia ammonium amounts anticodon aqueous solution aspartic acid biochemical biological CaCO3 carbon CH₂ chain chemical chert CO₂ concentration condensation contain COOH cyanoacetylene cytosine decomposition dust cloud electric discharge energy enzyme equilibrium escape layer evolution example formaldehyde formation formed gases genetic geological glutamic acid glycine H₂ H₂N H₂O hydrocarbons hydrogen cyanide hydrolysis hydrolyzed important inorganic L. E. Orgel limestone living organisms material mechanism membranes metabolism meteorites methane minerals mixture molecules N₂ NH₂ nitrogen nucleic acids nucleotides O₂ obtained occur organic compounds origin oxidation oxygen pathways peptide phosphate phosphorylation photochemical photosynthesis planets polymers polynucleotides polypeptides prebiotic prebiotic synthesis Precambrian present pressure primitive atmosphere primitive earth primitive ocean purines reaction replication rocks Schopf Science sequence solar system structure sugars surface t-RNA temperature ultraviolet light volcanoes yield