DNA Replication & Repair MCAT Practice Question
Researchers investigate a cell line with a mutation in the MLH1 gene, which encodes a key mismatch repair protein. These cells exhibit microsatellite instability (MSI) and a high mutation rate. What is the consequence of defective MLH1 function on genome stability and the specific type of mutations that accumulate?
Answer choices
- AIncreased UV-induced thymine dimers that cannot be detected
- BInability to synthesize DNA during S phase
- CPersistent double-strand breaks that become progressively worse
- DAccumulation of insertion/deletion mutations in repetitive DNA sequencesCorrect answer
- EComplete prevention of cell division until mutations are resolved
- FIncreased point mutations resulting from impaired nucleotide excision repair
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