Question

From the given combinations of steps in PCR, identify the enzyme dependent step/s.

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

Answer 1

The Correct Option is D

Explanation of PCR Steps:

Denaturation (95°C):

• DNA strands separate (heat-dependent, no enzyme required)
• Non-enzymatic process

Annealing (50-65°C):

• Primers bind to template DNA
• Non-enzymatic process (hydrogen bonding)

Extension (72°C):

• Taq DNA polymerase adds nucleotides to synthesize new DNA strands
• Only enzyme-dependent step in PCR

Thus, the correct option is D: Extension only.