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Frequency/distribution of nucleotides/amino acids before selection

Dr.Ram Samudrala ram.samudrala at stanford.nojunkemail
Thu Nov 5 11:07:50 EST 1998


Donald Forsdyke <forsdyke at post.queensu.ca> wrote:

>But surely, as soon as a piece of DNA "thinks" of encoding a protein,
>selection becomes operative on the protein.

? But if there's no protein product how can selection be in effect?
(Assuming, for the moment, that the organism's fitness is primarily
determined by proteins.)

> 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,

It may have; DNA and RNA structure (for example) is also important to
the organism's fitness.  But I am referring to cases where the DNA and
the corresponding transcript (not necessarily the translated product)
is under no selective pressure in nature.

>(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).

I read your page the first time around, but I am not sure how it
answers my question, especially that point (i.e., there's no doubt
that once it becomes a protein-encoding gene selection is acting on
it).

--Ram

email at urls  ||  http://www.ram.org  ||  http://www.twisted-helices.com/th
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