If the map distance between genes A and B is 20 map units and the map distance between genes B and C is 35 map units, what is the map distance between genes A and C?
A)15 map units
B)55 map units
C)More information is needed to distinguish between 15 and 55 map units.
D)Gene C must be located on a different nonhomologous chromosome.

Question

Quizplus · Accepted Answer

In genetic mapping, the map distance between two genes reflects the frequency of recombination between them. If genes A and B are 20 map units apart, and genes B and C are 35 map units apart, the distance between A and C could be either the sum of the two distances (if B is between A and C) or the difference (if C is between A and B or vice versa). Without knowing the order of the genes, it's impossible to determine the exact distance between A and C.

If the Map Distance Between Genes a and B Is