Function of DNA Helicase In DNA metabolism, what is the primary role of DNA helicase?

Introduction / Context:Helicases are essential nucleic acid motor proteins in replication, repair, and recombination. They use NTP hydrolysis to destabilize base pairing and unwind DNA for downstream enzymes.

Given Data / Assumptions:

• Helicase acts ahead of replication forks.
• Strand separation is prerequisite for polymerase action.

Concept / Approach:Differentiate unwinding (helicase) from nick sealing (ligase) and backbone cleavage (nucleases). Helicase does not cut phosphodiester bonds; it disrupts hydrogen bonding between bases through mechanical translocation and energy usage.

Step-by-Step Solution:

Verification / Alternative check:In vitro helicase assays measure duplex unwinding; ligase shows nick sealing without unwinding capability.

Why Other Options Are Wrong:

• Tight interaction to prevent unwinding: opposite of helicase action.
• Breaking phosphodiester bonds: nuclease, not helicase.
• Joining fragments: ligase function.

Common Pitfalls:Confusing unwinding (hydrogen bonds) with cutting (phosphodiester bonds).

Final Answer:Unwind the double helix by separating complementary strands