During DNA replication, which enzyme is responsible for unzipping (separating) the two strands of the DNA double helix at the replication fork?

• A. Helicase
• B. DNA polymerase
• C. Primase
• D. DNA ligase

Answer: (A)

Verified step by step guidance

1. Understand the process of DNA replication, which involves unwinding the double helix and synthesizing new complementary strands.
2. Identify the role of each enzyme listed: DNA polymerase synthesizes new DNA strands, primase synthesizes RNA primers, DNA ligase joins Okazaki fragments, and helicase unwinds the DNA.
3. Focus on the step where the two strands of DNA are separated to allow replication to occur; this is the unzipping of the double helix at the replication fork.
4. Recall that the enzyme responsible for breaking the hydrogen bonds between complementary base pairs to separate the strands is helicase.
5. Conclude that helicase is the enzyme that unzips the DNA strands during replication, enabling other enzymes to synthesize new DNA.