The Origins of Life on the Earth |
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Page 123
... uridine at a similar rate ( a half - life less than 20,000 years under reasonable prebiotic conditions ) . This is a real difficulty if it is assumed that cytosine was required for nucleic acids in the first organism . Perhaps cytidine ...
... uridine at a similar rate ( a half - life less than 20,000 years under reasonable prebiotic conditions ) . This is a real difficulty if it is assumed that cytosine was required for nucleic acids in the first organism . Perhaps cytidine ...
Page 143
... Uridine ; Up ! = Uridine - 2 ' , 3 ' - cyclic pU , ———— ; Up , poration of inorganic phosphate , = Uridine - 3 ' , 5 ' - diphosphate . ( From phosphate ; pU = Uridine - 5 ' - phosphate ; Up = Uridine - 3 ' - phosphate ; pUp ! = Uri ...
... Uridine ; Up ! = Uridine - 2 ' , 3 ' - cyclic pU , ———— ; Up , poration of inorganic phosphate , = Uridine - 3 ' , 5 ' - diphosphate . ( From phosphate ; pU = Uridine - 5 ' - phosphate ; Up = Uridine - 3 ' - phosphate ; pUp ! = Uri ...
Page 172
... uridine HOH2 C ОН НО HN . B - L - uridine Fig . 13-7 . The optical isomers of ẞ - uridine . Changing from D- to L - ẞ - uridine involves inversion of each substituent in the plane of the furanose ring . If an attempt is made to insert L ...
... uridine HOH2 C ОН НО HN . B - L - uridine Fig . 13-7 . The optical isomers of ẞ - uridine . Changing from D- to L - ẞ - uridine involves inversion of each substituent in the plane of the furanose ring . If an attempt is made to insert L ...
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