Question

g genes a and b are 20 cM apart. Imagine a cross involving AAbb x aaBB. WHat would the genotype of their offspring be? if that offspring is test-crossed with an aabb individual, what would be the genotypes of the progeney and in what proportions

Answer 1

AaBb: Aabb: aaBb: aabb

4:4:4:4

1:1:1:1

Step-by-step explanation:

Alles for cross between AAbb x aaBB are -

AAbb - Ab, Ab, Ab, Ab

aaBB - aB, aB, aB, aB

a) Thus all 16 offspring that will be produced by crossing AAbb x aaBB would be AaBb

b) Now if a cross is carried out between "AaBb" and "aabb", the following offspring will be produced-

AaBb – AB, Ab, aB, ab

aabb- ab, ab, ab, ab

AB Ab aB ab

ab AaBb Aabb aaBb aabb

ab AaBb Aabb aaBb aabb

ab AaBb Aabb aaBb aabb

ab AaBb Aabb aaBb aabb

The genotypic ratio is

AaBb: Aabb: aaBb: aabb

4:4:4:4

1:1:1:1