Identify and explain steps ‘A&rsqu | Class 12 Biology Chapter Biotechnology Principles and Process, Biotechnology Principles and Process NCERT Solutions

A. Denaturation

B. Annealing

C. DNA synthesis or Extension of primers

PCR is a chain reaction because of newly synthesized DNA acts as templates for further DNA formation in the form of cycles. In each cycle, the duplex DNA strands are separated by the heat denaturation at 93- 95◦C and then it is cooled so that synthetic DNA primers can anneal to the complementary segments on each strand. The annealing temperature usually occurs at about 50- 70◦C; this annealing temperature should be low that enables the hybridization between primer and the template strand and should be high as to prevent the mismatched hybridization. Then DNA synthesis occurs at about 70-75◦C temperature and then this extension is obtained by DNA polymerase enzyme. The process is then repeated several times and the unit- length of the cycle doubles with every cycle.