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mDNA Mutations


name         Tor
status   student
age           20s

Question -   Since the mitochondria DNA  is inherited entirely from
your mother, would my mitochondric DNA be the  same as my great
grandmothers? How does this DNA change?
Mutations in DNA occur at random.  Usually there has to be some  mutagen (ie. 
radioactivity, UV rays) or a mistake in copying in just the right  place to 
cause a mutation.  This doesn't necessarily happen at a regular  rate.  But we 
can say that over a very long period of time, say a million  years, or 
100,000, or 10,000 years) a certain number of mutations are likely to  have happened. 
 The longer period of time between two sequences of DNA that  are being 
compared, the greater likelihood there is that a mutation will have  happened.  So, 
if you compare Neanderthal DNA to modern human DNA you see  about 20 
differences on average.  Between any two unrelated modern humans  there are about 6-8. 
 But mitochondrial DNA passes intact between mother  and child.  So your 
grandmother should have gotten her mtDNA intact from  her mother (your 
great-grandmother).  And so on.  It is unlikely that  in that small amount of time a 
mutation will have occurred mathematically  speaking.  COULD it have happened?  
Sure.  But it isn't  likely.  
K VanHoeck
Assuming no mutation, yes. I don't know what the mutation rate of mitochodrial DNA is, 
but I would "guesstimate" that about one in 1,000 individuals would carry a newly 
arising mutation when compared compared to their mother. You might try doing a search 
on Google for "mitochondrial DNA mutation rate".

Ron Baker, Ph.D.

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