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Re: organic conversations



> > Molecular biologists recognize that certain genes
> or proteins have a 
> > common ancestry, just as organismal biologists
> recognize that certain 
> > organs or appendages have a common ancestry.
> 
> Yes. They just shouldn't say "% homologous" when
> they mean "% identical". 

The problem is that in mol-bio, one has to distinguish
between ortho- and paralogs, between-species and
within-species (due to gene duplication) homology.
Doesn't really transfer well to anything outside
mol-bio... the display feathers of a lyretail are
paralogous to its body feathers, but the display
feathers of a bird-of-paradise are orthologous to
those of a lyretail.

But that's still not a very good reason to use
"homology" instead of "DNA sequence identity" or
"protein sequence identity". Indeed, that the latter
two are not identical would suggest that "homology"
should better be used as everyone does (doing
different things but descended from the same ancestral
item) in mol-bio too.


Eike


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