general question about PCR

Weining, Song WeininS at
Mon Nov 15 06:40:37 EST 1999

I have answered similar questions a few times in the last decade. It's only
from the people who genuinely thought about PCR.  I hope I understand your
question correctly and don't make myself a fool.

It's true that the polymerase would run the whole length of the template
until something stops it, be it inhibitor, structure or just denaturing. 
But THIS happens mainly in the first cycle. The primers themselves would
define the border (length) of the PCR fragment in the following cycles. 
The fact is the PCR fragment is the major product whereas other products,
like in the first cycle and the rest, are proportionally too small to make
any REAL difference normally. No textbook talks about it, at least I have
seen anything yet.
As other people suggested, you need to draw it out on a big board. 

Song Weining
Leslie Research Centre
13 Holberton Street
PO Box 2282,
Toowoomba, QLD 4350

Phone: 61-7-46398880
Fax: 61-7-46398800
Email: weinins at

More information about the Methods mailing list