Persistence of separate mitochondrial genome

David Mathog mathog at seqaxp.bio.caltech.edu
Fri Sep 15 18:45:50 EST 2000

In article <8pr430$s9c$1 at mercury.hgmp.mrc.ac.uk>, Dr. Ram Samudrala <ram.samudrala at stanford.edu> writes:
>I would turn that around and ask: why do you think they should go to
>the nucleus?  It seems a system that works well initially evolved this
>way---what selective advantage do you see to those genes being in the
>nucleus as opposed to being in the mitochondrion.  

Advantages: Recombination and diploidy (or higher).   The genes of the
organelle needn't be perfectly adapted at all times - think about what
happens when one suffers a deleterious mutation.  Sex is good for the
genes, but organelles don't have sex, only cells containing organelles do. 

I also suspect that the repair of DNA mutations is much better for nuclear
genes.  Although that probably was't true the day the first organelle
crawled into the cytoplasm, the first two factors would lead to nuclear
migration of genes, and that would tend to break the DNA repair systems in
the organelle. 


David Mathog
mathog at seqaxp.bio.caltech.edu
Manager, sequence analysis facility, biology division, Caltech 


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