Multiple Choice
Human DNA cut with restriction enzyme A can be joined to which of the following DNA fragments?
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17. Mutation, Repair, and Recombination
DNA Repair
Multiple Choice
In the context of DNA repair and replication fidelity, how does DNA polymerase help prevent mutations during DNA synthesis?
A
By proofreading newly added nucleotides using its to exonuclease activity to remove mismatched bases
B
By directly reversing UV-induced thymine dimers through photoreactivation
C
By methylating mismatched bases to mark them for replacement by mismatch repair proteins
D
By excising bulky DNA adducts using nucleotide excision repair endonucleases
Verified step by step guidance1
Understand that DNA polymerase is the enzyme responsible for synthesizing new DNA strands by adding nucleotides complementary to the template strand.
Recognize that during DNA synthesis, errors can occur when incorrect nucleotides are incorporated, potentially leading to mutations if not corrected.
Know that DNA polymerase has a proofreading function, which involves a 3\' to 5\' exonuclease activity that allows it to remove incorrectly paired nucleotides immediately after they are added.
This proofreading activity works by detecting mismatched bases, excising them from the newly synthesized strand, and then resuming DNA synthesis with the correct nucleotide.
Differentiate this proofreading mechanism from other DNA repair processes such as photoreactivation, methylation-based mismatch repair, or nucleotide excision repair, which are separate pathways and not functions of DNA polymerase itself.
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