In a data set to determine crossover frequency between the sc,ec,and cv genes in Drosophila,the crossover frequency between ec and sc = 0.15,and ec and cv = .25.The number of double crossover flies was 15 out of 500 flies.Assuming sc,ec,cv is the respective order of the genes,what can we conclude from this result?
A) The coefficient of coincidence is near zero.
B) The expected number of crossovers and the observed numbers are different.
C) The genes are tightly linked.
D) The coefficient of coincidence is near one.
E) There is a large amount of interference between these genes.

Question

Quizplus · Accepted Answer

The coefficient of coincidence (CoC) is the ratio of observed double crossovers to expected double crossovers. In this case, there were 15 observed double crossovers out of 500 flies, which gives an observed frequency of 0.03. The expected frequency of double crossovers can be calculated as (crossover frequency between ec and sc) x (crossover frequency between ec and cv) = 0.15 x 0.25 = 0.0375. The CoC is therefore 0.03/0.0375 = 0.8. Since the CoC is close to one, it indicates that there is little interference between these genes. Therefore, the correct answer is D.

In a Data Set to Determine Crossover Frequency Between the Sc,ec,and