In Polymerase chain reaction, multiple copies of required gene or DNA are synthesised. It is actually, in vitro method of amplification of desired DNA sequence.
Two sets of primers are required in each cycle.
Role of primers and enzyme DNA polymerase- Primers are chemically synthesised small fragment of DNA, that is complementary to the target region of DNA. In PCR primers are required to direct replication towards each other.
Enzyme extend one primer that become template for the other, which ultimately lead to the exponential increase of the target or desired DNA sequence.