The Polymerase Chain Reaction (PCR)
The first two rounds of PCR do
not generate short DNA products
corresponding to the interval between the primers. Note that the first round of PCR in step (c) generates long fragments that run
off the 5' ends of the target
region. In the second round in
step (e), extension again
generate variable length strands. Only in the third round in step (g) are 'unit length' products generated
uniformly for the first time.
Compare the process illustrated in this diagram with
that in the simplified diagram.,
which shows the process as it works beginning in the fourth round of
Figure © 2002 by
al. ; text © 2009 by Steven M.