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Talk:Chain termination method

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Technique discussed[edit]

The technique described here is a modern 4-in-1 technique that has all for ddNTP's in the same reaction, each one differnetly labled. Then we have the picture to the right showing the more 'classical' method of running each separate ddNTP reaction separately and running them on four separate lanes, not fluoresence needed. I think we should make light of this difference and make things more clear, any ideas? -Adenosine- 08:10, Mar 8, 2005 (UTC)

Agreed, I'll try to make a note of it in the article --Kinglz 02:40, 8 Jun 2005 (UTC)

Clarification: It would be great if someone could change that image User:Adenosine was talking about so that the nucleotides (ATGC) are not shown in color since it makes it seem as if the DNA is fluorescently labeled instead of radiolabeled. --Kinglz 04:10, 8 Jun 2005 (UTC)

Cycle-sequencing is not PCR[edit]

What is described in the article is cycle sequencing. Please note that cycle sequencing uses a single primer that anneals in a unique position on the template DNA which is then extended by the sequencing polymerase. Because only one primer is used, products from earlier cycles do not become templates in subsequent cycles. This means that the amplifiction is linear, not exponential. That is, there is no "Chain Reaction".

Also cycle sequencing was a modification of the chain termination method. Chain termination sequencing does not require any thermal cycling. The original chain termination sequencing method predates the invention of PCR. So thermal cyclers were not commonly found in labs. That means, in the bad old days, we didn't have cycle sequencing and had to whomp up an enormous batch of DNA template (by today's standards) and do a single cycle of sequencing on it.

--Phillip 21:33, 13 Jun 2005 (UTC)

My mistake, thanks for pointing that out. --Kinglz 02:01, 18 Jun 2005 (UTC)

Sure. But I see that another reference indicating that PCR is a necessary part of chain termination sequencing:

"In the chain termination method, the polymerase chain reaction(PCR) is used to produce millions of cloned pieces of DNA."

Should that not also be changed?

--Phillip SanMiguel 16:14, 20 Jun 2005 (UTC)

Oh, bah I was too busy just changing the second section I didn't notice the first. --Kinglz 00:07, 21 Jun 2005 (UTC)