Multiple Choice
During the eukaryotic cell cycle, when does DNA replication occur?
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8. DNA Replication
Overview of DNA Replication
Multiple Choice
In the overview of DNA replication, what is the primary role of helicase?
A
It relieves torsional strain ahead of the replication fork by cutting and rejoining DNA strands.
B
It unwinds the DNA double helix by breaking hydrogen bonds between complementary base pairs, separating the two strands.
C
It synthesizes new DNA strands by adding nucleotides to the 3′ end of a growing strand.
D
It seals nicks in the sugar-phosphate backbone to join Okazaki fragments into a continuous strand.
Verified step by step guidance1
Step 1: Understand the process of DNA replication, which involves unwinding the double helix, separating the strands, synthesizing new strands, and joining fragments.
Step 2: Identify the function of helicase in this process. Helicase is an enzyme that acts at the replication fork.
Step 3: Recognize that helicase breaks the hydrogen bonds between complementary base pairs, which separates the two DNA strands and allows replication machinery to access the single strands.
Step 4: Differentiate helicase's role from other enzymes: DNA gyrase relieves torsional strain, DNA polymerase synthesizes new strands, and DNA ligase seals nicks between Okazaki fragments.
Step 5: Conclude that the primary role of helicase is to unwind the DNA double helix by breaking hydrogen bonds, enabling strand separation necessary for replication.
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