In a genetic mapping experiment, the crossing over frequencies between four linked genes P, Q, R, and S were recorded as follows: P and S = 35 % Q and R = 15 % P and R = 25 % Q and S = 25 % R and S = 10 % P and Q = 10 % Based on this data, identify the correct linear order of these genes on the chromosome.

Step-by-step solution

Crossing over frequencies are directly proportional to the distance between genes on a chromosome, where 1 % crossing over equals 1 map unit. The maximum recombination frequency is between P and S ( 35 % ), which means P and S are located at the two extreme ends of the gene map. The distance between P and R is 25 % , and between R and S is 10 % . Since 25 + 10 = 35 , R must be located between P and S. The distance between P and Q is 10 % , and between Q and R is 15 % . Since 10 + 15 = 25 , Q must be located between