Re: Babies with three parents?

David Harper wrote:
> 
> The fact that they have their own DNA, independent of the nucleus of the

> cell, is intriguing, and has led biologists to hypothesise that the 
> mitochondria are actually descendants of ancient bacteria which formed a

> symbiotic relation****p with other organisms early in the history of 
> multi-cellular life on Earth.
> 

Looking at things from the point of view of a mitochondrion I would 
expect that events such as oogenesis, fertilisation and division of the 
host cell line would be well-nigh indiscernible - the host cytoplasm 
would simply be an expanding environment of extremely long durability 
but one shared with other mitochondria.  In such cir***stances, however, 
each viable mutation would found a new mitochondrial cell-line (for want 
of a better term) which would share this environment with its fellows. 
Over the course of many host generations one would, therefore, expect a 
host-cell line to contain many genetically diverse mitochondria.  But in 
such cir***stances mt-DNA analysis would become difficult if not 
impossible and yet we are told sensible answers can be obtained from 
this technique.  Presumably there must be a mechanism which enables a 
single mitochondrial strain to achieve dominance - but what is it?


-- 
Ian

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