Malcolm wrote:
>  wrote
> >
> > Of course I am correct.  Definitions of 'recessive' and 'dominant'
are
> > defined by classical genetics.  As it turns out, the underlying
> > mechanisms for these phenomenon are extremely varied.  I have
taught
> > genetics for nearly 30 years and have found that students
frequently
> > confuse the basic observations with the underlying mechanisms.  As
we
> > have witnessed in this thread.  The main point I was trying to make
is
> > that the term "recessive gene" is quite meaningless.
> >
> Well my great uncle and great aunt, both siblings of my maternal
> grandmother, had red hair. My maternal grandmother had brown hair, as
did my
> mother, as do I. However if you look very closely at my hair you will
find
> the occasional ginger strand.
> Is it meaningless to say that I probably carry a recessive gene for
red
> hair?

It would be more accurate to refer to the recessive allele.  The term
'gene' usually refers to all of the its alleles in a population.  Eg
each of us carry two copies of the cftr gene (named after the disease
cytic fibrosis).  Many people carry at least one defective copy of the
gene but they are normal because the disease gene is recessive to the
major allele.  Disease is found in those two copies of the disease
gene.

Mike Syvanen
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