Evolution by Gene Duplications: from the Origin of the Genetic Code to the Human Genome
Evolution ab simplecioribus ad complexiora is based on duplications. In a working live system novelties almost never emerge by chance. New genes, exons, or even smaller functional units typically originate with minute changes in the duplicate(s) of preexisting sequences. Extant gene and protein sequences often harbor the periodicity that unambiguously points to their duplicationbased origins (Ohno, 1987, 1988). Here we consider two fundamental paradoxes associated with duplications. The first paradox dates back to the origin of encoded protein synthesis, and it can be explained away by what arguably was the single most important duplication event in the history of life, the duplication of a presumable short precursor of a transfer RNA that shaped it into a major adaptor of the genetic code. The second paradox belongs to the realm of already quite complex and advanced life; it concerns survival of gene duplicates per se and appears to be most pronounced in the human genome. In a sense, the entire history of life (as we see it presently) can be said to lie in between the above two series of events.
KeywordsGenetic Code Acceptor Stem Groove Side Strand Asymmetry Extra Gene Copy
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