Kimmo K K Fredriksson
kfredrik at cc.helsinki.fi
Tue Jul 11 08:24:38 EST 1995
On Mon, 10 Jul 1995, Nathan A Buettner wrote:
> In article <3tqqbv$gvg at oravannahka.Helsinki.FI> you wrote:
> > Would someone please explain me the purpose of the diploid genome, and
> > the method the cell uses to decide if some particular gene is dominating
> > or not? Does the cell always use only the other one of the two competing
> > alleles, or both ones, if neither is dominating?
> > Thanks!
> In general, a "dominant" allele produces a functional gene product, while
> a "recessive" allele produces a non-functional gene product, due to some
> mutation or defect.
> If both alleles are the same (homozygous) and therefore produce the
> same functional gene product, a "dominant" phenotype is observed. If
> you have 1 dominant and 1 recessive allele, the dominant allele still
> produces an adequate amount of gene product to produce a dominant
> phenotype (usually).
> If you have 2 recessive alleles, no functional gene product can be
> produced. If you have 2 functional alleles that produce different gene
> products (eg. blood antigens A and B), you have "co-dominance" in which
> both gene products function simultaneously (eg. type AB blood).
> nab1 at utdallas.edu
So, the evolutionary reason to have diploid genes could be to provide
backup facility against the faulty (recessive) genes, right? This point
of view suggests that the AB blood could be some kind of mistake, altought
it works fine?
I don't know if this sounds stupid (I know very little about biology :-)
BTW: Is there FAQ for this group?
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