Question

Mention the number of primers required in each cycle of polymerase chain reaction (PCR). Write the role of primers and DNA polymerase in PCR.

Answer 1

Each cycle of PCR requires two sets of primers. 

Role of Primers: Primers are complementary to the regions of DNA. They anneal to both the strands of DNA which are then extended using nucleotides. 

Role of DNA Polymerase: 

(i) The enzyme extends the primers using the nucleotides provided in the reaction and the genomic DNA as template. 

(ii) DNA polymerase used in PCR is thermostable and is called Taq polymerase. It is obtained from the bacterium Thermus aquaticus.