Multiple Choice
Which enzyme breaks the hydrogen bonds between the strands of parental DNA during DNA replication?
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17. Mutation, Repair, and Recombination
DNA Repair
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What is the role of the enzyme ligase in DNA replication?
A
It synthesizes RNA primers to initiate DNA synthesis.
B
It removes incorrectly paired nucleotides during proofreading.
C
It unwinds the DNA double helix to allow replication to occur.
D
It joins Okazaki fragments by forming phosphodiester bonds between DNA fragments on the lagging strand.
Verified step by step guidance1
Understand that DNA replication involves synthesizing a new strand complementary to the original DNA strand, which occurs continuously on the leading strand and discontinuously on the lagging strand.
Recognize that the lagging strand is synthesized in short segments called Okazaki fragments, which need to be joined together to form a continuous strand.
Identify the enzyme responsible for joining these Okazaki fragments by forming covalent bonds between the sugar-phosphate backbones of adjacent DNA fragments.
Recall that DNA ligase catalyzes the formation of phosphodiester bonds, effectively sealing the nicks between Okazaki fragments to create a continuous DNA strand.
Differentiate the role of DNA ligase from other enzymes: it does not synthesize RNA primers (that's primase), does not proofread (that's DNA polymerase), and does not unwind DNA (that's helicase).
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