AP Biologyeasymcq1 pt
Which is true of DNA polymerase proofreading?
A.It removes mismatched nucleotides as they are added
B.It repairs the lagging strand only
C.It prevents all mutations
D.It rewrites RNA into DNA
Explanation
Core Concept
Many DNA polymerases improve replication fidelity through 3′→5′ exonuclease proofreading that removes mismatched nucleotides shortly after they are added. Proofreading substantially lowers the error rate, and post-replicative mismatch repair lowers it further. Very low overall mutation rates such as roughly one error per billion bases should not be attributed to proofreading alone.
Correct Answer
AIt removes mismatched nucleotides as they are added
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