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Multiple Choice
Which of the following best describes the function of the enzyme helicase?
A
It unwinds the DNA double helix during DNA replication.
B
It removes RNA primers from the DNA strand.
C
It joins Okazaki fragments together on the lagging strand.
D
It synthesizes new DNA strands by adding nucleotides.
Verified step by step guidance
1
Understand the role of helicase in DNA replication: Helicase is an enzyme responsible for unwinding the DNA double helix, which is a critical step in DNA replication. This allows the replication machinery to access the single-stranded DNA templates.
Differentiate helicase from other enzymes involved in DNA replication: For example, DNA polymerase synthesizes new DNA strands by adding nucleotides, ligase joins Okazaki fragments on the lagging strand, and other enzymes like primase lay down RNA primers.
Focus on the unwinding process: Helicase breaks the hydrogen bonds between complementary base pairs (adenine-thymine and guanine-cytosine) in the DNA double helix, creating two single strands that serve as templates for replication.
Clarify why helicase does not perform the other functions listed: Helicase does not remove RNA primers (this is done by DNA polymerase I in prokaryotes) or join Okazaki fragments (this is done by DNA ligase). Its sole function is unwinding the DNA.
Conclude that the correct description of helicase's function is: 'It unwinds the DNA double helix during DNA replication.' This is the most accurate and specific answer based on its role in the replication process.