PCR question

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thewax
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PCR question

Post by thewax » Tue Dec 23, 2008 1:50 am

Why is there a need for PCR when there is helicase-dependent amplification??????
In http://en.wikipedia.org/wiki/Helicase-d ... lification, wikipedia states that HDA takes longer than PCR. My question is WHY?????? [Even though the helicase might unwound it slowly (as evident in DNA replication) it's not as if the DNA polymerase can elongate the growing DNA strand any faster (again refer to DNA replication), right?????]

thewax
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Post by thewax » Wed Dec 24, 2008 7:52 pm

Can anyone help with this question????????

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Post by blcr11 » Thu Dec 25, 2008 11:18 am

That wiki article was probably posted by someone from the kit manufacturer. You probably should consider it a bit of advertising. I don't know anyone using this alternative to pcr. The only "advantage" I can see is the ability to run everything at one temperature, and I don't see that as a great plus. If the method was obviously superior to pcr it would be widely used already. I suspect it does not work as well as advertised.

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Post by thewax » Thu Dec 25, 2008 11:37 pm

Thanks!!!!!! :)

But why wouldn't it????
I mean, compare the helicase and DNA polymerase to those used in DNA replication (they are the same, and in DNA replication, they move really fast), right?????????

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Post by mith » Fri Dec 26, 2008 7:36 pm

http://www.nature.com/embor/journal/v5/ ... 00200.html

lacks refinement, doesn't work on long seqs, but it's interesting enough to be in nature
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thewax
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Post by thewax » Sat Dec 27, 2008 5:08 pm

hmm... so HDA is pretty efficient....., right?????

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Sepals
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Post by Sepals » Fri Jan 09, 2009 4:46 pm

The article lies. PCR does denature DNA, at around 95C. So therefore it must become unwound for the two strands to separate. Never use wikipedia as an academic resource, it's too untrustworthy and contrary to what some people say, it is not fully protected. I know from experience, it can be very hard to keep correct info on a page and permanently rid it of nonsense, as someone can easily vandalise it again.
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Re:

Post by Sepals » Fri Jan 09, 2009 4:49 pm

thewax wrote:Thanks!!!!!! :)

But why wouldn't it????
I mean, compare the helicase and DNA polymerase to those used in DNA replication (they are the same, and in DNA replication, they move really fast), right?????????
PCR is around 4 hours max if you use the maximum number of cycles (40) and normally 3 hours long. Surely 3 - 4 hours isn't too long to wait. Inbetween you can get on with other lab work.
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Post by thewax » Sat Jan 10, 2009 10:48 pm

cool!

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