Question

Which of the following shows the correct sequence of steps in polymerase chain reaction (PCR)?

• A. Denaturation, extension and annealing
• B. Annealing, extension and denaturation
• C. Extension, denaturation and annealing
• D. Denaturation, annealing and extension

Answer 1

The correct option is D Denaturation, annealing and extension

Polymerase chain reaction (PCR) is a method for the amplification of specific DNA sequences.

There are three steps in PCR.

• Denaturation: The double stranded DNA is separated using high temperature (${94}^{o}C$)
• Annealing: As DNA polymerisation reaction needs a 3' free end of nucleotide, primers are added to serve the purpose. The primers are annealed to the template strands of the DNA
• Extension: DNA-dependent DNA polymerase is used for elongation and extension of the primers. Thermostable DNA polymerases like the Taq polymerase is used for this process