Re: Seeds, semen, gametes and new life
- From: "Owl" <takowl@xxxxxxxxx>
- Date: Mon, 19 Dec 2005 18:38:14 -0500 (EST)
I think the type of aging that we see is not due to individual cells
aging - you may well be able to take a body cell from an 80 year-old,
and it would be indistinguishable from that of an 18-year old. What we
see is more the whole collection starting to break down - there is not
an infinitely replacing supply of all cells, and human bodies weren't
"designed" to last as long as we often make them. At a cellular level,
clearly we don't age as such.
Having said that, there are theories of cellular aging. I'm no expert
on these things, but I'll briefly cover one idea. On the ends of
chromosomes are little bits of DNA called telomeres. These are
important in cell division, and may have a protective function, but
they are not completely replicated. So each time the cell divides, they
get shorter. In germ-line cells (which make gametes), however, an
enzyme called telomerase adds to them.
Bacteria, having circular DNA, don't have to worry about telomeres.
.
- References:
- Seeds, semen, gametes and new life
- From: Paul Pfalzner
- Seeds, semen, gametes and new life
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