On 25/11/2006, at 3:45 PM, David Hobby wrote:
[EMAIL PROTECTED] wrote:
...
The genome is already messy. The notion that are chromosomes have
a neat lineup of genes is incorrect. There are insertions into
the middle of genes (introns). Many genes are spread over
discontinuous aspects of a single chromosome. Some insertions
into the middle of genes destroy function but many do not.
Yes, I know that. But if everybody's genome is messy
in the same way, then their chromosomes can still match
up quite well. Are there variations between people in
terms of what/where the introns are?
Yep. Even people with pretty extreme translocation can breed (less
successfully sometimes, but they can...).
I wish Alberto would chime in, but it seems that you don't
understand the question: "Isn't it sometimes bad when an
individual has a pair of chromosomes that don't match up
well?" (Which would be produced if their parents had
different numbers of various genes, right?)
I answered it, although maybe not clearly enough.
As far as I can tell, the answer is that it's not that
bad.
That was the answer, yes.
(Although I get the sense that we don't yet understand
enough about the role of wrapping/unwrapping DNA to give
a definitive answer.)
We don't know how it works so well, we don't understand the
mechanism. But we know it works better than our predisposition
towards order would normally think it could.
It's certainly bad if it gets to the
point where chromosomes don't segregate properly at meiosis,
but that's when the match ups between chromosome pairs are
really poor.
Yep.
Of course, the majority of conceptions don't make it to breeding age
(about half don't even implant...) so it seems that a lot can go
wrong. But it's also true that a lot can go wrong with it still working.
Charlie.
_______________________________________________
http://www.mccmedia.com/mailman/listinfo/brin-l
