Gene Duplication question
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11-05-2015, 08:28 PM
Gene Duplication question
Okay, so the more I look into evolution (I'm new to in depth study on it) , I am absolutely amazed at how beautifully it connects life together.

I recognize that Gene Duplication is a major mechanism for new DNA being added to the geneome, and thus is an important part of evolution on the large scale. The great part is, even if the duplicate has a bad mutation, the organism isn't harmed becuase it has the original gene as well.

However also know that Downs syndrome can be caused by having an extra copy of chromosome 21. This has me sort of stumped on the idea of gene duplication. If it's just an extra copy, why is it harmful? Shouldn't there be no real effect on the individual?

I know I'm missing something and would like some clarification.
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11-05-2015, 08:51 PM
RE: Gene Duplication question
(11-05-2015 08:28 PM)Itsdemtitans Wrote:  Okay, so the more I look into evolution (I'm new to in depth study on it) , I am absolutely amazed at how beautifully it connects life together.

I recognize that Gene Duplication is a major mechanism for new DNA being added to the geneome, and thus is an important part of evolution on the large scale. The great part is, even if the duplicate has a bad mutation, the organism isn't harmed becuase it has the original gene as well.

However also know that Downs syndrome can be caused by having an extra copy of chromosome 21. This has me sort of stumped on the idea of gene duplication. If it's just an extra copy, why is it harmful? Shouldn't there be no real effect on the individual?

I know I'm missing something and would like some clarification.

An extra copy of an entire chromosome contains duplication of many, many genes. It is also a structural difference in the reproductive machinery.

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12-05-2015, 01:25 AM
RE: Gene Duplication question
(11-05-2015 08:28 PM)Itsdemtitans Wrote:  Okay, so the more I look into evolution (I'm new to in depth study on it) , I am absolutely amazed at how beautifully it connects life together.

I recognize that Gene Duplication is a major mechanism for new DNA being added to the geneome, and thus is an important part of evolution on the large scale. The great part is, even if the duplicate has a bad mutation, the organism isn't harmed becuase it has the original gene as well.

However also know that Downs syndrome can be caused by having an extra copy of chromosome 21. This has me sort of stumped on the idea of gene duplication. If it's just an extra copy, why is it harmful? Shouldn't there be no real effect on the individual?

I know I'm missing something and would like some clarification.

Straight from Utah University site:
Quote:Having an extra copy of this chromosome means that individuals have three copies of each of its genes instead of two, making it difficult for cells to properly control how much protein is made. Producing too much or too little protein can have serious consequences. Genes on chromosome 21 that specifically contribute to the various symptoms of Down syndrome are now being identified.

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12-05-2015, 03:10 AM
RE: Gene Duplication question
Ah, I see now. Thanks for the clarification
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12-05-2015, 11:17 PM
RE: Gene Duplication question
Hi Itsdemtitans

Gene's are complicated things, for many you either have a good one or you don't so you are OK or you are not. For many a single good gene may be able to make what you need, two copies of that good gene will make twice as much but for some things that’s no big deal, too much Vitamin C for example is no problem your body just discards the excess.

That’s not always the case though, regulatory gene’s produce substances that are needed in specific quantities to work properly. They guide the placement of other components in the forming body for example. Too little and you’re in trouble, too much likewise so you need to have just two good copies (one from your mother and one from you father). Trisomy (having three copies) causes an excess and so the body does not form correctly as in Downs Syndrome.

Gene duplication does not have to mean a full copy of a chromosome rather you might just have a piece of a chromosome duplicated, this gives you two copies of some gene’s and so you have fodder for evolution to work on without removing what you need, as you say one of the copies can be modified without stopping your body producing what it needs as the other one is still there to do the job.

Russell
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