Question

which role does the enzyme helicase play in dna replication?
○ unwinds the two dna strands
○ cuts new dna strands away from old
○ checks for mistakes in replication
○ brings in new nitrogenous bases

Explanation:

To determine the role of helicase in DNA replication, we analyze each option:

• "unwinds the two DNA strands": Helicase's function is to break the hydrogen bonds between the two DNA strands, unwinding the double helix to expose the template strands for replication.
• "cuts new DNA strands away from old": This is not a function of helicase; enzymes like nucleases or ligases are involved in such processes (if applicable), but not helicase.
• "checks for mistakes in replication": Proofreading is done by DNA polymerase, not helicase.
• "brings in new nitrogenous bases": DNA polymerase adds nucleotides (which contain nitrogenous bases) to the growing strand, not helicase.

So the correct option is the one stating helicase unwinds the two DNA strands.

Answer:

A. unwinds the two DNA strands