Two pairs of fruit flies crossed. Females are heterozygous for genes A and B, and males are recessive for these genes.

Two pairs of fruit flies crossed. Females are heterozygous for genes A and B, and males are recessive for these genes. In the offspring, the following class ratio was obtained: first cross – 41.5% AaBb: 8.5% Aabb: 8.5% aaBb: 41.5% aabb; second cross – 41.5% Aabb: 8.5% AaBb: 8.5% aabb: 41.5% aaBb. Determine: 1) genes A and B are in cis or trans position; 2) the distance between genes A and B in percentage of crossing over in females in the first and second crosses.

1) In the first crossing, in the female, A and B are localized on one chromosome, and in the other – a and b (cis-position), in the second – genes A and b in one chromosome, and genes a and B in the other (trans- position). 2) The distance between genes A and B is equal to 17% crossing over.

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