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dsRNA

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dsRNA

Postby mith » Thu Oct 25, 2007 8:00 am

What would be the advantages and disadvantages of using dsRNA vs DNA?

I'm curious because it seems RNA has very little primer/polymerase problems compared to DNA in replication.
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Postby MrMistery » Thu Oct 25, 2007 11:45 am

you means viruses that use dsRNA?
Well, it is the best choice really, combining the high-error rate that is key to viruses with the stability of a double stranded molecule.
What do you mean primer/polymerase problems?
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Postby mith » Thu Oct 25, 2007 4:36 pm

I mean as genetic storage for eukaryotes. For example we know polymerase only adds in one direction and needs primers etc, but RNA can just be synthesized on the spot. Why didn't we just evolve and refine that mechanism?
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Postby MrMistery » Fri Oct 26, 2007 5:41 pm

very high error rate in RNA synthesis. When DNA appeared, it probably had a much smaller error rate and imposed itself as the energy holder. Can't think of anything else..
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Re: dsRNA

Postby dna89 » Fri Oct 26, 2007 9:09 pm

dsRNA attains A form, that would be too much compact and could be almost inaccessable for the polymerase withiut proper helicase. you couldn't have the RNAi defence system and rna is much more mutation prone. donno whether im right or wrong!
Last edited by dna89 on Mon Oct 29, 2007 6:45 pm, edited 1 time in total.
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Postby MrMistery » Sat Oct 27, 2007 7:02 pm

i don't think A form is that compact
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Postby dna89 » Mon Oct 29, 2007 6:48 pm

may be you are right. but when DNA or RNA is in A form, the melting point increases. i think, it indicates the compactness.
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Postby biohazard » Tue Oct 30, 2007 9:48 am

In addition to the high error rate of RNA synthesis, I think one profound aspect is the great stability of DNA. For various reasons, (such as the DNA helix itself, ans well as proteins that assist DNA packaging) DNA is much more stable than RNA in just about all cases I can think of - be that heat, UV light or chemicals for example). dsRNA would surely be more stable than single stranded, but it still has the inherent unstability when compared to the DNA. RNA is also degraded rapidly by many enzymes (of which several are defence elements against RNA viruses.)

However, it could've been a thin line between RNA and DNA when life was still young, but today RNA simply does not work as a long termstorage for genes - save from cases like some viruses. The proof reding and packaging mechanisms of DNA have evolved to be quite nifty ;)

If I think about a multi cellular organism that had RNA as its genome, the whole thing would probably be a cancer, if it just could live long enough to have all those errors in its genome to facilitate cancer cell differentiation :P
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Postby MrMistery » Tue Oct 30, 2007 11:54 am

dna89 wrote:may be you are right. but when DNA or RNA is in A form, the melting point increases. i think, it indicates the compactness.

A form is more compact. That is a known fact. I just said that i don't think it is that compact to make protein-RNA interactions impossible
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