Gene order from recombination frequencies
Recombination frequencies between three linked genes are A–B = 10%, B–C = 15%, and A–C = 25%. What is the gene order?
Answer A: explanation for every choice
A
Correct. The two shorter distances add up to the longest (10 + 15 = 25), so B lies between A and C.
B
If A were in the middle, B–C would equal B–A + A–C, or 35%.
C
If C were in the middle, A–B would be the largest distance.
D
Three pairwise distances are enough to determine the order.
TakeawayThe gene in the middle is the one whose two distances add up to the largest.
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Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID bb166.