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Frequency/distribution of nucleotides/amino acids before selection

Donald Forsdyke forsdyke at post.queensu.ca
Wed Nov 4 11:28:10 EST 1998


> The premise is that the amino acid composition is different in a gene
> prior to selection (i.e., before selective pressures arise for the
> protein encoded by the gene) and after selection. 

But surely, as soon as a piece of DNA "thinks" of encoding a protein,
selection becomes operative on the protein. Can there really be a period
prior to selection kicking in?

> That's related to my question. You can argue selection cannot be
> present in a gene that isn't functional.  But I think it is a
> difficult question to answer, which is why I asked.

   What you seem to be missing out is that selection may have acted on
the piece of DNA before it "thinks" of becoming a protein-encoding gene,
(and even after it becomes a protein-encoding gene selection may be
acting on it for genomic reasons discussed elsewhere:
http://post.queensu.ca/~forsdyke/evolutio.htm).

Sincerely, Donald Forsdyke




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