DNA Replication & Repair MCAT Practice Question
A 28-year-old woman presents to the genetics clinic for evaluation of a family history concerning for cancer predisposition syndrome. She reports that her brother died of acute myeloid leukemia at age 19, and multiple relatives have had early-onset solid tumors. Physical examination reveals short stature, microcephaly, and café-au-lait spots. Laboratory studies show increased chromosomal fragility when fibroblasts are exposed to diepoxybutane (DEB), a crosslinking agent. She is counseled regarding increased sensitivity to chemotherapy due to a defect in her DNA repair pathway. Which of the following DNA repair mechanisms is primarily defective in this patient's underlying condition?
Answer choices
- ANucleotide excision repair (NER), which recognizes and removes bulky DNA lesions
- BBase excision repair (BER), which corrects spontaneous deamination and oxidative damage
- CMismatch repair (MMR), which identifies and corrects replication errors
- DHomologous recombination and interstrand crosslink repair mediated by the Fanconi anemia pathwayCorrect answer
- ENon-homologous end joining (NHEJ), which rapidly ligates double-strand breaks
- FTranslesion synthesis polymerases, which bypass unrepaired lesions during replication
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