Which of the following steps are catalysed by Taq polymerase in a PCR reaction ?A. Denaturation of template DNA.B. Annealing of primeres to template DNAC. Extension of primer end on the template DNAD. All of the above.

Which of the following steps are catalysed by Taq polymerase in a PCR

1.	Which of the following steps are catalysed by Taq polymerase in a PCR reaction ?A. Denaturation of template DNA.B. Annealing of primeres to template DNAC. Extension of primer end on the template DNAD. All of the above.
Answer» In polymerase chain reaction polymerisation or extension step is catalysed by Taq polymearse enzyme, PCR is carried out in the following three steps (i) Denaturation the double standard DNA is denatured by applying high temperature of `95^(@)C` for 15 seconds Each separated single standard strant now acids as template for DNA synthesis. (ii) Annealing Two sets of primers are added which anneal to the 3 and of each separated strand. primers act as initiators of replication. (iii) DNA polymerase extends the primare by adding nucleotides complementary to the template provided in the reaction. A thermostable DNA polymerase (Taq DNA polymerase) is used in the reaction which can tolerate the high temperature of the reaction. All these steps are repeated many times to obtain several copies of desired DNA.