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Multiple Choice
What is the function of the enzyme topoisomerase in DNA replication?
A
Relieving strain in the DNA ahead of the replication fork caused by the untwisting of the double helix.
B
Elongating new DNA at a replication fork by adding nucleotides to the existing chain.
C
Reattaching the hydrogen bonds between the base pairs in the double helix.
D
Building RNA primers using the parental DNA strand as a template.
Verified step by step guidance
1
Understand the context of DNA replication: DNA replication is the process by which a cell duplicates its DNA, creating two identical copies. This process involves several enzymes that each have specific roles.
Identify the role of topoisomerase: Topoisomerase is an enzyme that helps manage the topology of DNA during replication. It is crucial for relieving the tension that builds up ahead of the replication fork as the DNA double helix unwinds.
Explain the problem of DNA supercoiling: As the DNA unwinds, it can become overwound or supercoiled, which creates tension and can hinder the replication process. This is where topoisomerase comes into play.
Describe the action of topoisomerase: Topoisomerase works by making temporary cuts in the DNA strands, allowing them to rotate and relieve the tension. It then reseals the cuts, maintaining the integrity of the DNA.
Clarify the specific function of topoisomerase in the context of the options given: The primary function of topoisomerase during DNA replication is to relieve the strain in the DNA ahead of the replication fork, which is caused by the untwisting of the double helix. This is distinct from other functions like elongating DNA, reattaching hydrogen bonds, or building RNA primers.