PCR consists of three successive steps: (i) Denaturation, (ii) Primer annealing and (iii) Extension of primers. In denaturation, the temperature of 93-95 ∘ C is maintained for melting the two strands of a DNA molecule. In annealing, the primers attach to the target sequence of DNA. In extension, new strands of DNA are synethesised using Taq polymerase.