Two genes A and B on the same chromosome show a recombination frequency of 30%. The observed double‑crossover frequency is 6%. Calculate the coefficient of coincidence and the interference.
Answer
Coefficient of coincidence 0.67; interference 0.33
The correct answer is Coefficient of coincidence 0.67; interference 0.33 — Interference = 1 – coefficient of coincidence = 1 – 0.6667 = 0.3333 (≈0.33).
Step-by-step solution
- Calculate expected double‑crossover frequency assuming independent intervals: "expected = (recombination ≡ 0.30) * (recombination ≡ 0.30) = 0.09" (9%).
- Use observed double‑crossover (0.06) to find coefficient of coincidence: "COC = observed / expected = 0.06 / 0.09 = 0.6667" (≈0.67).
- Interference = 1 – coefficient of coincidence = 1 – 0.6667 = 0.3333 (≈0.33).
Common mistake: Using the recombination frequency directly as the expected double‑crossover probability
Concept tested: Linkage – recombination frequency
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