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Originally Posted by BioSci
This is not so much a new discovery but more of a realization that such changes are important in regulating how genes are expressed.
These differences are not changes in the gene sequences - they are changes in how genes are turned on and off.
That this occurs has been known a long time - for example each different tissue in one's body expresses a different set of genes but all the our genes are present in all cells.
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(emphasis mine) I understand this, but I don't think it's what the newspaper is saying. The article is about how the occurence of mutations when DNA is replicated are so common that the DNA itself is completely different in each cell, rather than just which genes are expressed. As in, right from the point where the zygote begins to divide several mutations are already occuring in each new cell which is created, so that by the time a person is XYZ age the DNA in any one of their cells bears little resemblance to the DNA in any other cell. That was how I understood it, and that's why I was so surprised - because this theory seems to completely go against so much that scientists previously held to be true about the genome - and also why I was very sceptical when I heard nothing else about it.
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Originally Posted by slang
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The geneticists must abandon their view of a stable genome, in which changes are sickly exceptions.
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I very much doubt that that is a fair characterisation of the modern view of how the genome acts. To me it feels a bit exaggerated |
The part about all changes being sickly exceptions does sound quite exaggerated, but surely it is true to say that the genome is generally considered to be stable? As BioSci said, the same genes are (or were always thought to be) present in every cell. On the other hand, seeing as I really don't know much about this subject it's probably a lot more complicated than I think, so that could be a massive oversimplification.
tdvance, I like your junk DNA idea - that was something I hadn't considered, but it seems like it could make sense. Isn't there a possible problem with the fact that junk DNA varies so much between individuals though? I mean that even though some people have junk DNA that others don't, and everyone has different amounts of it in completely different patterns, very few people end up with twelve fingers (or whatever)?
Thanks for all your help
