Review Article
Jan C Biro
Abstract
Compilation of previously discussed main ideas about the evolution of genetic code is presented and completed with bioinformatical analyses of codon usage frequency data from 113 species.It is suggested that the recent 64/20 Genetic Code (Nirenberg) and the associated redundancy in translation developed successively from a much simpler, primitive Code containing only a few AT-rich codons. Codon boundaries were not yet defined so the codons were translated overlappingly. The subsequent addition of GC bases (especially those added at 1st and 3rd codon positions) provided the conditions for the physicochemical definition of codon boundaries and the development of non-overlapping translation. This view is supported by bioinformatics studies in the recent literature as well as by novel findings.