Which PCR Step Synthesizes Complementary DNA Strands

Question

Which PCR step synthesizes complementary DNA strands?
A)Add DNA polymerase and nucleotides at 72°C.
B)Cool DNA to between 50°C and 65°C.
C)Add primers.
D)Heat target DNA to 94°C.
E)Repeat the cycle of heating and cooling.

Accepted Answer

The addition of DNA polymerase and nucleotides at 72°C in the extension step of PCR synthesizes complementary DNA strands. The other steps (addition of primers, cooling, heating, and cycling) all contribute to the overall PCR process but do not directly synthesize the complementary DNA strands.