Genetics Desperately waiting for replies

[saltrock]

Genetics!Desperately waiting for replies

In drosophilia,blackbody colour is recessive to grey body colour.A geneticist had 3 pairs of flies with grey body designated A,B and C.He crossed A and b and obtained 109 grey bodied flies,A and C gave 80 grey bodied and 28 black bodied whilst B and Cgave 76 grey bodies flies.Explain with reason the genotype of A,B and C.

 

[lurflurf]

let X repersent the grey gene
and x the black gene
XX,Xx,xX are grey phenotype
xx is black phenotye
XX*Xx gives 100% grey
XX*XX gives 100% grey
Xx*Xx gives 75%grey 25% black
A*C is mixed so A and C are Xx
A*B=B*C so B is XX

 

[wais]

Based on the results of the crosses, we can determine the genotypes of A, B, and C as follows:

A: A must be homozygous for the dominant grey body trait, as when crossed with b (homozygous for the recessive black body trait) all of the offspring were grey bodied. This means that A must have the genotype AA.

B: B must also be homozygous for the dominant grey body trait, as when crossed with c (heterozygous for grey body and black body), the majority of the offspring were grey bodied. This suggests that B also has the genotype BB.

C: C must be heterozygous for the grey body trait, as when crossed with both A and B, a mixture of grey and black bodied offspring were produced. This means that C has the genotype Bc.

In summary, the genotypes of A, B, and C are AA, BB, and Bc, respectively.