Describe the polymerase chain reaction

The first step of PCR requires the target gene to be located using primers. Primers are short nucleotide sequences that are the complementary to either side of the target gene. The DNA sample containing the target DNA is heated which caused the double helix to unwind. It is then subsequently cooled so that the primers can bind to either side of the gene. DNA polymerase is then added to replicate the gene and the process is then repeated for multiple cycles in multicycler PCR machine which can produce millions of copies in relatively short space of time.