Researchers monitored chromosomes 1 and 2 in two hundred cel

Researchers monitored chromosomes 1 and 2 in two hundred cells (RS/rs) going through meiosis. An analysis of the chromosomes, eventually recovered from the daughter cells, indicated that 138 showed no indication of crossovers; 46 indicated a single crossover event; 12 a double crossover event, and 4 a triple crossover event. What was the average number of crossovers between genes on the recovered chromosomes?

Solution

Answer:

1. NCO = 138

SCO = 46

DCO = 12

TCO = 4

Average number of crossovers between R and S:

0 * (138/200) + 1 * (46/200) + 2 * (12/200) + 3 * (4/200)

= 0 + 0.23 + 0.12 + 0.06 = 0.41