Multiple Choice
In DNA replication, what is the primary role of DNA ligase?
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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 primase at the replication fork?
A
To add DNA nucleotides to the growing strand in the direction using the template strand
B
To synthesize short RNA primers that provide a free for DNA polymerase to begin DNA synthesis
C
To seal nicks between Okazaki fragments by forming phosphodiester bonds in the sugar-phosphate backbone
D
To unwind the parental DNA double helix by breaking hydrogen bonds ahead of the replication fork
Verified step by step guidance1
Understand the context of DNA replication, where the replication fork is the site at which the parental DNA double helix is unwound to allow synthesis of new strands.
Recall that DNA polymerase cannot initiate synthesis of a new DNA strand on its own; it requires a primer with a free 3\' hydroxyl (3\' OH) group to add nucleotides.
Identify the enzyme primase as the one responsible for synthesizing short RNA primers complementary to the DNA template strand at the replication fork.
Recognize that these RNA primers provide the necessary free 3\' OH group that DNA polymerase uses to start adding DNA nucleotides in the 5\' to 3\' direction.
Distinguish primase's role from other enzymes: it does not add DNA nucleotides itself, does not seal nicks (that is ligase's job), and does not unwind DNA (that is helicase's job).
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