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Author Topic: What if identical twins had different mitochondrial DNA?  (Read 3771 times)

Offline David Cooper

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It's in the title - normal identical twins in that their main 46 chromosomes are identical, but with mitochondrial DNA from different sources. Would they still look near identical? Would they be equally good at running? Might one be fat and the other thin with identical diet and exercise? Have experiments been done on this in animals?


 

Offline cheryl j

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Re: What if identical twins had different mitochondrial DNA?
« Reply #1 on: 28/02/2014 18:36:29 »
I think they would look the same, unless one twin's mitochondria were out right genetically defective. There could be differences in metabolic rate, but you can also increase the number of mitochondria through aerobic exercise.
 

Offline evan_au

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Re: What if identical twins had different mitochondrial DNA?
« Reply #2 on: 28/02/2014 20:56:25 »
If the twins are identical, they split from a single fertilised egg, with a single set of nuclear DNA.

However, the egg has numerous mitochondria, each with its own genetic code. When a cell divides, the mitochondria also divide, but may be unevenly partitioned between the daughter cells. This could result in a different genetic mix of mitochondria between the twins.

It is also possible that a new mitochondrial mutation could occur in one of the twins.
 

Offline cheryl j

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Re: What if identical twins had different mitochondrial DNA?
« Reply #3 on: 01/03/2014 16:54:30 »
I had never heard that every mitochondria has its own genetic code. In fact I thought that was the whole point of studying mitochondria DNA, that it was the same all the way down the maternal line except for mutations.
I have read about very rare instances of mitochondria from the sperm somehow getting into the egg.
 

Offline David Cooper

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Re: What if identical twins had different mitochondrial DNA?
« Reply #4 on: 01/03/2014 18:18:36 »
The idea was to have genetically altered identical twins (or clones) such that the only significant difference between them is the mitochondrial DNA (which would ordinarily be near identical too). What I really want to know is how much differences in mitochondrial DNA can contribute to differences between individual people, and this would obviously be easiest to test with modified clones, which means animal testing.
 

Offline cheryl j

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Re: What if identical twins had different mitochondrial DNA?
« Reply #5 on: 03/03/2014 01:59:08 »
Yes, clones as you described might be a good test, except that low oxygen stimulates mitochondria to reproduce and it might mitigate any differences.
« Last Edit: 03/03/2014 02:01:03 by cheryl j »
 

Offline evan_au

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Re: What if identical twins had different mitochondrial DNA?
« Reply #6 on: 03/03/2014 10:02:27 »
Quote
What I really want to know is how much differences in mitochondrial DNA can contribute to differences between individual people
Mitochondria generate the ATP which powers the cell. So the effects will probably be in anything which powers the cell metabolism - especially muscle, brain & eyes, which have especially high energy demands.

We can see the impacts of mitochondrial diseases; I imagine that mitochondrial function could affect activity and lethargy - but this will appear differently in different organs.

Many of the mitochondrial genes are actually expressed by DNA in the cell's nucleus (in humans, 13 proteins in the mitochondrial DNA, and approximately 1500 in the cell nucleus). I have heard that different species have quite different division of genes between their mitochondria and the cell nucleus.
 

Offline David Cooper

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Re: What if identical twins had different mitochondrial DNA?
« Reply #7 on: 03/03/2014 19:09:45 »
"Symptoms include poor growth, loss of muscle coordination, muscle weakness, visual problems, hearing problems, learning disabilities, heart disease, liver disease, kidney disease, gastrointestinal disorders, respiratory disorders, neurological problems, autonomic dysfunction and dementia."

That's quite a lot there that could potentially also be affected more subtly by small differences which aren't classed as diseases, but which could enhance or suppress athletic performance. The reason I'm thinking about all this is of course the fuss being made at the moment about children being born to three parents, where one supplies the mitochondrial DNA to prevent a mitochondrial disease being passed on by the "other" mother.
 

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Re: What if identical twins had different mitochondrial DNA?
« Reply #7 on: 03/03/2014 19:09:45 »

 

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