From: John Mikes <[email protected]>
To: [email protected]
Sent: Tuesday, April 7, 2015 2:03 PM
Subject: Re: Histones (proteins that form the scaffolding around which DNA
wraps itself may also themselves be involved in heredity processes
Apologies: MITOCHONDRIUM - I S - and mitochondria -are. JM
On Tue, Apr 7, 2015 at 4:14 PM, John Mikes <[email protected]> wrote:
Liz:"passed on" - do you mean survives AS IS? I think whatever is added
incubates into the complexity of the new creature into fitting, not 'as was' in
the mother. And- I think mitochondria IS a cell within the larger one in
symbiotic life. Chris is most likely right: FROM THE MOTHER only. And it is
adjusted into the new complexity as well.
This is the reason why mitochondria are used as a yardstick to measure the
natural rate of mutation (e.g. the genetic drift). Because all animals
exclusively get their own mitochondria from their mother -- e.g. NOT by sexual
reproduction, which effectively is a shuffling of the genetic heritage of both
portions of both parents DNA. The mitochondria DNA instead only ever comes from
the maternal line and for this reason it makes a good genetic clock. A clock
that can be used to estimate how old a species is, or that can tell a story of
how a species almost went extinct some 70,000 years ago -- as happened to our
own species. The reason e know this is by studying the genetic diversity of
human mitochondrial DNA.Interestingly the Y chromosome, which all males of a
species carry and exclusively get from the paternal side, can also function as
a yardstick, again because it is unaffected by sexual reproduction. If an
offspring has the Y chromosome (e.g. is a male) it got it from its father and
never ever got it from its mother. For all our other chromosomes what we get is
the sexually reshuffled recombined deck of cards, some of which came from each
parent.Does this make any sense?Chris
JM
On Tue, Apr 7, 2015 at 12:18 AM, LizR <[email protected]> wrote:
Anything in the egg cell, or donated at any point during gestation from the
mother (in mammals, at least) can be passed on, I assume. (What about
mitochondria?)
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