During DNA replication, which enzyme is primarily responsible for "unzipping" the double helix by breaking hydrogen bonds between complementary bases at the replication fork?

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

Answer: (D)

Verified step by step guidance

1. Understand the process of DNA replication, which involves unwinding the double helix to allow each strand to be copied.
2. Identify the role of enzymes involved in replication: Primase synthesizes RNA primers, DNA ligase joins Okazaki fragments, and DNA polymerase synthesizes new DNA strands.
3. Focus on the enzyme responsible for breaking hydrogen bonds between complementary bases to separate the two DNA strands at the replication fork.
4. Recall that the enzyme which 'unzips' the DNA by breaking these hydrogen bonds is DNA helicase.
5. Conclude that DNA helicase is the primary enzyme responsible for unwinding the DNA double helix during replication.