Thanks Robin!

Dave Williams PROFDHW at AOL.COM
Mon May 12 04:51:09 CDT 1997


In a message dated 5/12/97 2:02:38 AM, Robin K Panza wrote:

>Changes between q and r are affected only by drift,
>which can be significant while they are uncommon.  Different frequencies
will
>result in different frequencies of the two recessive HZs, which will affect
the
>relative selective force.
>
>
>>brings me back to my original question: In a classical system, how do we
know
>>that two recessive alleles are identical if any number of possible
mutations
>>may produce nonfunctional proteins which would have the same effect
>
>This part is easy to answer--by DNA sequencing.  The difference in sequence
>will expose the PZ.  The only vague area is whether two identical sequences
>are truly homologous (decendents of the same original mutation event, rather
>than the same mutation having occured twice in the past).  Granted, the
latter
>should be very rare, and so identical DNA sequences are assumed (via Occam's
>Razor) to be from the same mutation history.
>
>Robin K Panza

Thanks, Robin, for noticing me. You'll see, upon careful inspection, that my
question emphasizes "a classical system". My notion of such is genetics in
the period up to, and including, the Beadle and Tatum "one gene-one enzyme"
hypothesis. In a classical system DNA sequencing is not available. So, in
classical genetics one would simply have to put up with the notion that
recessives may be PZ or HZ (not that it would make any difference).

Don't mind me I'm just a pedagogue on a busman's holiday.

Dave Williams
Science Division
Anne Arundel Community College
Arnold, MD 21012
Vmail: 410-541-2265
Email: profdhw at aol.com




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