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Old 01-06-2011, 04:08 AM
dzero dzero is offline
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In thousands of genes, RNA is not a faithful copy of DNA

Apparently, the central dogma of genetics is that RNA translates what is encoded in DNA into proteins. But research presented at the annual meeting of the American Society of Human Genetics says otherwise.

On average, each person has 4,000 genes which RNA does not accurately reproduce.

Quote:
Scientists already knew that every now and then RNA letters can be chemically modified or edited—sort of the molecular equivalent of adding an umlaut to some letters. But those RNA editing events are not common.

What Li and her colleagues discovered is quite common. RNA molecules contained misspellings at 20,000 different places in the genome, with about 10,000 different misspellings occurring in two or more of the people studied. The most common of the 12 different types of misspellings was when an A in the DNA was changed to G in the RNA. That change accounted for about a third of the misspellings.
Direct link to abstract

Last edited by dzero; 01-06-2011 at 04:09 AM.
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Old 01-06-2011, 05:37 AM
Isamu Isamu is offline
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Mental note: Implement spell check autocorrect in Animal ver2.0. That should fix things.

Serious note. Interesting but I don't think it's that big of a deal. It has been long known that this kind of thing occurs, but now we just have a better idea of the frequency of occurrence, right?
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Old 01-06-2011, 06:00 AM
dzero dzero is offline
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Quote:
Originally Posted by Isamu View Post
Mental note: Implement spell check autocorrect in Animal ver2.0. That should fix things.

Serious note. Interesting but I don't think it's that big of a deal. It has been long known that this kind of thing occurs, but now we just have a better idea of the frequency of occurrence, right?
That's not the impression I got from their saying that the central dogma of genetics may be overturned. That sounds a bit more serious but I'm not geneticist.

We know that there are short strands of RNA (iRNA IIRC) that interfere with the building of certain proteins and therefore act as a regulation mechanism. We also know that the full gene sequence for a protein can be spread over numerous base pairs that are fairly remote from one another.

The article said
Quote:
Scientists already knew that every now and then RNA letters can be chemically modified or edited—sort of the molecular equivalent of adding an umlaut to some letters. But those RNA editing events are not common.
But I think that was the perceived extent of it.

This is incredibly interesting if the proteins formed from misread DNA are actually functional. That would mean that having the right protein in some cases DEPENDS on the DNA being misread. That is pretty wild stuff.

It also means that there is some other mechanism that must be conserved from an evolutionary point of view that causes RNA to misread the DNA in just the right way but only with respect to certain genes. THAT will be incredibly interesting I think.
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Old 01-07-2011, 08:55 AM
Smeghead Smeghead is offline
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One theme that, IMHO, is emerging from the era of genomics is the incredible complexity of genetic regulation. Basically, if you can imagine a way for a gene to be regulated, if you look hard enough, you'll find it somewhere. Messing with regulation makes for quick and easy evolutionary adaptations - much faster and simpler than trying to redesign proteins. RNA is also clearly becoming increasingly important and taking on all kinds of roles that people a generation ago never would have guessed. I suspect that in the near future, many mutations that were assumed to be important in the protein will be reexamined and found to be important in the RNA instead.

So while this is very interesting and worthy of study, I can't say it surprises me terribly.
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Old 01-07-2011, 05:09 PM
Hari Seldon Hari Seldon is offline
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But isn't each RNA molecule used once to make a protein and then destroyed? In that case, those errors will be one-off and most proteins will be correct.

I guess this illustrates that DNA reproduces much more reliably than RNA. The changeover to DNA genome must have been just as significant a change as some others, such as getting a nucleus, multi-cellularity etc.
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Old 01-07-2011, 08:55 PM
armedmonkey armedmonkey is offline
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meh. First off, the genetic code is redundant, so a simple substitution mutation or mistranslation probably won't do much. Changing a third A to a G in the codon won't even change 18 of the 20 amino acids. For example, Leucine is coded by UUA, UUG, CUU, CUC, CUA, and CUG. Changing one of those As to a G isn't going to do a damn thing - it's still leucine.

Second, most proteins are made up of thousands of amino acids (aprroximate size range is 500 - 27,000 amino acids) so even if a single amino acid is coded incorectly, the protein probably won't change much.

Last edited by armedmonkey; 01-07-2011 at 08:56 PM.
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