In F2, 87 black-bodied flies with curved wings and 269 normal flies were obtained from crossing a normal female

In F2, 87 black-bodied flies with curved wings and 269 normal flies were obtained from crossing a normal female Drosophila with a male with a black body and curved wings. How are traits inherited? Genotypes of home flies and genotype and phenotype of F1?

Let A be a gray body (normal) and a black.

B – normal wings, b – curved.

1) Find the splitting in by the F2 phenotype:

87 + 269 = 356.

87/356 = 1/4 (approx). 1 – 1/4 = 3/4, respectively, splitting 1: 3.

This happens when two heterozygotes are crossed (Aa or Bb), but since such a splitting occurs at once according to two signs, it can be concluded that the genes encoding them form a linkage group, that is, they are on the same chromosome. Accordingly, the genotypes F1 – AaBb.

2) Knowing the genotypes of the offspring, you can restore the genotypes of the parents.

The male has the genotype AAVB, respectively, the female is AABB.

Crossing scheme:

Parents: AB || AB x ab || ab.

Gametes: AB x ab,

F1 genotypes: AB || ab. Gametes F1: AB, ab x AB, ab,

F2 genotypes: AB || AB, 2 AB || ab, ab || ab.

There is no other splitting (for example, there are no individuals with bent wings and a gray body); accordingly, there was no crossing over.