Abstract
An evolutionary scheme is postulated in which a primitive code, involving only guanine and cytosine, would code for glycine (GG), alanine (GC), arginine (CG) and proline (CC). From each of these amino acids and their codons, there evolves a family of related amino acids as the code expands. The four families are: (1)alanine valine, leucine, isoleucine, phenylalanine, tyrosine, methionine and tryptophane; (2)proline, threonine and serine; (3)arginine, lysine, and histidine; (4)glycine, serine, cysteine, glutamic acid, glutamine, aspartic acid and asparagine. Except for the glycine relation to glutamic acid and aspartic acid, all amino acids are related by chemical similarities in their side chains. Glycine not having a side chain would permit a more complex set of substitutions.
Article PDF
Similar content being viewed by others
References
Crick, F. H. C.: 1968,J. Molec. Biol. 38, 367.
Hartman, H.: 1975,Origins of Life,6, 423.
Crothers, D. M., Seno, T. and Soll, D.: 1972,PNAS 69, 3063.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Hartman, H. Speculations on the evolution of the genetic code II. Origins Life Evol Biosphere 9, 133–136 (1978). https://doi.org/10.1007/BF00931410
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00931410