Multiple Choice
In DNA replication, which enzyme builds (synthesizes) new DNA strands by adding nucleotides to the growing chain?
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8. DNA Replication
Overview of DNA Replication
Multiple Choice
In an overview of DNA replication, what is the direct result of DNA ligase activity on the newly synthesized DNA strand?
A
It synthesizes RNA primers needed to initiate DNA synthesis on the lagging strand.
B
It adds nucleotides to the 3′ end of a growing DNA strand using a DNA template.
C
It unwinds the parental DNA double helix ahead of the replication fork.
D
It seals nicks in the sugar-phosphate backbone by forming phosphodiester bonds, joining Okazaki fragments into a continuous strand.
Verified step by step guidance1
Understand the role of DNA ligase in DNA replication, which is to join DNA fragments together.
Recall that during replication, the lagging strand is synthesized discontinuously in short segments called Okazaki fragments.
Recognize that these Okazaki fragments initially have nicks—breaks in the sugar-phosphate backbone—between them.
Know that DNA ligase catalyzes the formation of phosphodiester bonds between the 3′ hydroxyl end of one fragment and the 5′ phosphate end of the adjacent fragment.
Conclude that the direct result of DNA ligase activity is the sealing of these nicks, creating a continuous DNA strand on the lagging strand.
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