During DNA replication, which enzyme is primarily responsible for unzipping (separating) the two strands of the DNA double helix by breaking hydrogen bonds?

• A. DNA polymerase III
• B. DNA ligase
• C. Primase
• D. DNA helicase

Answer: (D)

Verified step by step guidance

1. Understand the process of DNA replication, which involves unwinding the double helix and separating the two strands to serve as templates for new DNA synthesis.
2. Identify the role of enzymes involved in DNA replication: DNA polymerase III synthesizes new DNA strands, DNA ligase joins Okazaki fragments, and primase synthesizes RNA primers.
3. Focus on the enzyme responsible for breaking the hydrogen bonds between complementary base pairs to separate the two DNA strands.
4. Recall that the enzyme which unzips the DNA by breaking hydrogen bonds is DNA helicase.
5. Conclude that DNA helicase is the primary enzyme responsible for unzipping the DNA double helix during replication.