Question

The correct order of steps in PCR is:
(A) Annealing,
(B) Denaturation,
(C) Extension

• A. (B), (A), (C)
• B. (A), (B), (C)
• C. (B), (C), (A)
• D. (C), (A), (B)

Hint:

Denaturation helps separate the two strands of DNA by breaking the hydrogen bonds, annealing helps the primer bind to its complementary sequence and extension helps in adding of nucleotides by DNA polymerase.

Answer 1

The Correct Option is B

Polymerase Chain Reaction (PCR) amplifies DNA through three primary steps:
• Denaturation: Heating DNA to 95°C separates double-stranded DNA into two single strands.
• Annealing: The temperature drops to 50-65°C, allowing primers to bind to complementary DNA sequences.
• Extension: At 72°C (optimal for Taq DNA Polymerase), DNA polymerase synthesizes new strands by adding nucleotides to the primers.
These steps are cyclically repeated to amplify target DNA regions. The sequence is Denaturation > Annealing > Extension.