Why are there two sexes? It’s a question that has long perplexed generations of scientists, but researchers from UCL have come up with a radical new answer: mitochondria.
Using a new mathematical model, the team led by Dr Nick Lane and colleagues from the UCL CoMPLEX, and the Research Department of Genetics, Evolution and Environment showed that inheriting mitochondria from only one parent – in effect, the ‘female’ – improves fitness by optimizing the interactions between the two genomes. The paper is published in Proceedings of the Royal Society B. Descended from free-living bacteria, mitochondria were swallowed whole by another cell between one and a half to two billion years ago. But despite being engulfed, these tiny power packs have retained their own tiny genome, encoding just a handful of proteins, all of which are necessary for generating energy in the cell.
The strangest thing about this odd arrangement is that cell respiration relies on proteins encoded by two genomes, the tiny mitochondrial genome and the nucleus, where most DNA is stored. For respiration to work properly, the two genomes must work together to encode proteins that interact with nanoscopic precision. This difference seems to be the deepest evolutionary difference between the two sexes...
IN: http://www.ucl.ac.uk/news/news-articles/1112/111208-Nick-Lane-mitochondria
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