COrrections on OOgenesis (was Immortality etc.)
popa0206 at PO-Box.McGill.CA
Sun Sep 24 12:25:39 EST 1995
Just to clear up a few things... that could be missleading.....
> Gregory Bloom <gjb at evolving.com> writes:
> There are a number of problems with the notion of "self-fertilized"
> sex cells being a "clone" of one's normal cells. Each gene actually
> consists of a pair of genes, one from each parent. Usually, only
> one of these two genes (alleles?) expresses itself. When egg cells are
> formed, a recombination occurs that "shuffles" the genes from each parent
> into two separate nuclei. One nucleus goes on to form the new egg cell,
> while the other nucleus is pushed into a non-functional cell called
> the corpus luteum, I believe.
Uhm according to the most basic understanding of Meiosis there are 4 products of this
process (ie. four cells each with a haploid chromsomes number) not two! The other three product s of
meiosis are re absorbed thereby allowing the cytoplasm of all four products to contribute to the
cytoplasm of one egg.
> If a different random selection of genetic
> material from a different egg cell is used to "fertilize" this egg,
This need not be done, there is a process known as parthenogenesis... whereby an unfertilized
mammalian egg cell can be stimulated to develop into a complete embryo.
> In each case where this gene had previously been recessive and
> therefore unexpressed,
Recessive does not equal unexpressed. It just means that you require two copies of the gene
to affect the phenotype away from the dominant phenotype. The gene product may be out competed
by the dominant form for binding of promoters, other proteins etc.
> Gregory Bloom mailto:gjb at evolving.com 303.740.5706(vox) 303.740.5800(fax)
> ESI, Southgate One Building, 6892 So. Yosemite Ct. Englewood, CO 80111 (rox)
Graham Dellaire Snail Mail:
Red Cross, Research
McGill University Montreal Blood Services
Faculty of Medicine 3131 Sherbrooke St. East
Div. of Experimental Medicine Montreal, QC, Canada
E-mail: popa0206 at po-box.mcgill.ca H1W 1B2
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