OBJECTIVE LIFE SCIENCE
MOLECULAR BIOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?
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It catalyzes the lengthening of telomeres.
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It synthesizes RNA nucleotides to make a primer.
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It unwinds the parental double helix.
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It joins Okazaki fragments together.
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Explanation:
Detailed explanation-1: -On the lagging strand, DNA synthesis restarts many times as the helix unwinds, resulting in many short fragments called “Okazaki fragments.” DNA ligase joins the Okazaki fragments together into a single DNA molecule. Helicase opens up the DNA at the replication fork.
Detailed explanation-2: -These small pieces of newly synthesized DNA (called Okazaki fragments after their discoverer) are joined by the action of DNA ligase, forming an intact new DNA strand.
Detailed explanation-3: -Primase enzyme binds itself at the end of the leading strand. This primer acts as the starting point of DNA synthesis. Hence, ligase is used on the lagging strand.
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