In Drosophila, the recessive dp allele of the dumpy gene produces short, curved
ID: 191073 • Letter: I
Question
In Drosophila, the recessive dp allele of the dumpy gene produces short, curved wings, while the recessive allele bw of the brown gene causes brown eyes. In a testcross using females heterozygous for both of these genes, the following results were obtained:
wild-type wings, wild-type eyes 178
wild-type wings, brown eyes 185
dumpy wings, wild-type eyes 172
dumpy wings, brown eyes 181
In a testcross using males heterozygous for both of these genes, a different set of results was obtained:
wild-type wings, wild-type eyes 247
dumpy wings, brown eyes 242
a. What can you conclude from the first testcross?
b. What can you conclude from the second testcross?
c. How can you reconcile the data shown in parts a and b ? Can you exploit the difference between these two sets of data to devise a general test for synteny in Drosophila?
d. The genetic distance between dumpy and brown is 91.5 m.u. How could this value be measured?
Explanation / Answer
a. From the first test cross it can be concluded that this is dihybride cross. Two different characteristics has appreared. The cross occured in 9:3:3:1 ratio.
b. It can be concluded that the cross has made between two different characteristics. Here, result have come in 1:1 ratio.