Polymerase chain reaction MCQ - Practice Questions with Answers

Polymerase chain reaction proceeds in a fixed thermal cycle: denaturation first separates the double-stranded DNA into single strands; annealing then allows primers to bind to the target sequences; extension follows, where DNA polymerase synthesises the new strand. Starting with annealing is wrong because primers cannot bind properly until the DNA strands are separated. Placing extension before annealing is also wrong because polymerase needs an attached primer. Extension cannot be the first step for the same reason.