Molecular Biology/Genetics USMLE Step 1 Practice Question
When a cloned DNA fragment is used as a probe, a restriction fragment length polymorphism (RFLP) is revealed in the region adjacent to the centromere of chromosome 21. Four haplotypes exist: A, B, C, and D. An AB female and a CD male have an ACC child with trisomy 21. Nondisjunction most likely occurred during which of the following?
Answer choices
- AThe child during the first mitotic division
- BThe father during meiosis IICorrect answer
- CThe father during meiosis I
- DThe mother during meiosis I
- EThe mother during meiosis II
- FThe child during meiosis I
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