During the amplification of gene using PCR, the enzyme Taq DNA polymerase used between annealing and extension. The polymerase chain reaction is consists of three steps (i) Denaturation, (ii) Annealing, and (iii) Extension. In the first step, the double-stranded DNA denatured into single-stranded DNA. In the second step, small DNA primers are attached to a specific site on the template DNA. In the third step, taq DNA polymerase binds on the short double-stranded region and starts the DNA synthesis.