The Origins of Life on the Earth |
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Page 96
... cyanate is independent of pH between pH's of 5 and 9 , because the reactive species are ammonia and cyanic acid . HN = C = O + NH3 → · [ ~ HN - E - NH ; ] → H , N - E - NH2 The equilibrium constant at 25 ° C for the reaction H2N_C_NH ...
... cyanate is independent of pH between pH's of 5 and 9 , because the reactive species are ammonia and cyanic acid . HN = C = O + NH3 → · [ ~ HN - E - NH ; ] → H , N - E - NH2 The equilibrium constant at 25 ° C for the reaction H2N_C_NH ...
Page 108
... cyanate to give cytosine in quite good yield ( 20 % ) , but that the more obvious reaction of cyanate with aminoacrylonitrile does not work . HCEC - CEN < NH3 -NCO H2N - CH = CH - C = N N -NCO pyrimidines NH2 H2N CH || 0 = C CH N N H H ...
... cyanate to give cytosine in quite good yield ( 20 % ) , but that the more obvious reaction of cyanate with aminoacrylonitrile does not work . HCEC - CEN < NH3 -NCO H2N - CH = CH - C = N N -NCO pyrimidines NH2 H2N CH || 0 = C CH N N H H ...
Page 140
... Cyanate has not been used successfully either in the formation of peptide or phosphodiester bonds , although organic isocyanates are often used as condensing reagents in synthetic chemistry . Cyanate has been used in one prebiotic ...
... Cyanate has not been used successfully either in the formation of peptide or phosphodiester bonds , although organic isocyanates are often used as condensing reagents in synthetic chemistry . Cyanate has been used in one prebiotic ...
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