Emergence of template-and-sequence-directed (TSD) syntheses: I. A bio-geochemical model.
A biogeochemical model for the evolution of template-and-sequence-directed (TSD) syntheses of biological templates (proto-RNAs) and catalysts (peptides) is described. A fluctuating environment characterized by hydrating (cool) and dehydrating (warm) phases with cycles of consecutive organic reactions, as well as a constant supply of the polymeric building blocks is assumed. The scenario starts with the catalyzed formation of a primordial population of small random peptides, based on the relatively-ineffective mineral catalysts. The resulting peptides initiate a catalytic takeover process, during which the catalytic functions are gradually taken over by peptides. The evolution of TSD peptides is based on a combination of Lahav's (1991) co-evolution and Moller and Janssen's (1990) specific recognition sites hypotheses. During the emergence of TSD systems the fraction of TSD peptides and proto-RNA constituents rises from almost insignificance to dominance in a TSD Reactions Takeover. The TSD system is characterized by autocatalysis, positive feedback loops and a primordial genetic code. The model is the basis for a computer program (Part II of present series).
Lahav
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The Hebrew University of Jerusalem, The Faculty of Agriculture, Rehovot, Israel.
Nir
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D001483:Base Sequence; D002384:Catalysis; D019020:Directed Molecular Evolution; D019143:Evolution, Molecular; D008903:Minerals / Q000737:chemistry*; D008954:Models, Biological; D000069497:Origin of Life; D010455:Peptides / Q000737:chemistry*; D012313:RNA / Q000138:chemical synthesis*; D012333:RNA, Messenger / Q000138:chemical synthesis*; D012343:RNA, Transfer / Q000138:chemical synthesis*; D013698:Templates, Genetic
D008903:Minerals; D010455:Peptides; D012333:RNA, Messenger; D012313:RNA; D012343:RNA, Transfer