Question

The following test cross produces the progeny shown: Aa Bb x aa bb Progeny are as follows: 10 Aa Bb, 40 Aa bb, 40 aa Bb, 10 aa bb. We’re the A and B alleles in the Aa Bb parent in coupling or in repulsion? Please explain how this concept is understood and how the solution is found. I’m extremely confused about this, thank you!

Answer 1

Given that the following test cross produces the progeny with the following genotypic proportions.

AaBb x aabb -> 10 Aa Bb (recombinant) , 40 Aabb (parental), 40 aa Bb (parental), 10 aabb (recombinant)

The percent recombination between A and B loci is

= the number of recombinants*100/ total number of offspring = 20*100/ 100 = 20%

The genetic distance between the A and B locus = percent recombination = 20 map units

were the genes in the AaBb parent in coupling or in repulsion?

The genes in the AaBb parent in repulsion because the number of parental are higher than that of the recombinants.