Question

The genes for miniature wings (m) and garnet eyes (g) are approximately 8 map units apart on chromosome 1 in Drosophila. Phenotypically wild-type females (m + g / mg +) were mated to miniature-winged males with garnet eyes.
Part A

Which of the following phenotypic classes reflect offspring that were generated as a result of a crossover event?

Select all that apply.

garnet eyes
wild type
miniature wings
miniature wings, garnet eyes
Part B

If 800 offspring were produced from the cross, in what numbers would you expect the following phenotypes?

__wild type : __ miniature wings : __ garnet eyes : __ miniature wings, garnet eyes

Enter your answer as the number of flies of each phenotype separated by a colon (example: 100:300:100:300).

Answer 1

The following phenotypic classes reflect offspring that were generated as a result of a crossover event

• wild type

• miniature wings
• garnet eyes

Explanation:

When the miniature wings and garnet eyes links up with the 8 map unit that are present between them. After that the presence of two recombinant classes must complement together and make 8% of total i.e. they contribute 4% each. together the parental classes make up to 92% by contributing 46% one.

This can be understood through a phenotypic ratio calculation, which can be expected from it.

wild type: 4% x 800 = 32

miniature wings: 46% x 800 = 368

garnet eyes: 46% x 800 = 368

miniature wings, garnet eyes: 4% x 800 = 368