Question

determine the order of the three genes and explain how the order was determined.

Phenotype	Number of Individuals
wfm	5
+++	7
+fm	4
w++	0
w+m	2
+f+	1
wf+	0
++m	2

Answer 1

From the data given above we can deduce the following:

1. Parental phenotypes are wfm (7) and +++ (7), the gamates with highest frequency.
2. Double cross-overs are w++ (0) and wf+ (0), the gamates with lowest frequency.

Using the above deductions, we conclude that the order of the genes is wmf because the double cross-over moves the middle allele from one sister chromatid to another placing the non parental allele on the chromosome between the two flanking parental alleles.