What role does helicase play in DNA replication?

• A. It synthesizes RNA primers needed to initiate DNA synthesis on the leading and lagging strands.
• B. It adds nucleotides to the growing DNA strand in the $5\prime$ to $3\prime$ direction using the template strand.
• C. It unwinds the double helix by breaking hydrogen bonds between complementary bases, separating the two strands at the replication fork.
• D. It joins Okazaki fragments by forming phosphodiester bonds to create a continuous DNA strand.

Answer: (C)

Verified step by step guidance

1. Identify the function of helicase in the context of DNA replication by understanding the overall process of DNA synthesis.
2. Recall that DNA replication requires the separation of the two strands of the double helix to serve as templates for new strand synthesis.
3. Recognize that helicase is the enzyme responsible for unwinding the DNA double helix by breaking the hydrogen bonds between complementary base pairs, thus separating the two strands at the replication fork.
4. Distinguish helicase's role from other enzymes involved in replication, such as primase (which synthesizes RNA primers), DNA polymerase (which adds nucleotides), and DNA ligase (which joins Okazaki fragments).
5. Conclude that helicase's primary role is to unwind the DNA helix, enabling the replication machinery to access the single-stranded DNA templates.