The Theory of PCR

Here three steps. These PCR steps are repeated for approximately 30 or 40 cycles. This is done on an automated PCR thermal cycler or PCR machine. The PCR thermal cycler quickly heats and cools the PCR reaction mixture.

PCR Denaturation at about 94C

PCR Step 1

In this PCR step the double strand melts to single stranded DNA

PCR Annealing at about 54C

PCR Step 2

In this PCR step the primers bind to the single strand created in the previous PCR step.

PCR extension at about 72C

PCR Step 3

The PCR polymerase adds dNTP's from 5' to 3', reading the template from 3' to 5' side, to make two double stranded molecules. The PCR steps are repeated.