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 relationship 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 circumstances, 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 circumstances 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 Hotmail is for spammers. Real mail address is igoddard at nildram co uk