in drosophila gray body color is dominant over ebony body co

in drosophila, gray body color is dominant over ebony body color, while long wings are dominant over vestigial wings. work the following crosses through the F2 generation and determine phenotype ratio for each generation. assume that P1 is homozygous a) gray, long * ebony, vestigial

b)gray, vestigial * ebony, long c) gray, long * gray ,vestigial

can you give me a explanation and solution?

Solution

Assume that the gene coding for gray body is, G and the gene coding for ebony is, g; and G is dominant over g. Similarly, the gene coding for long wings is L and the gene coding for vestigial wings is, l. The genotype of the parental drosophila is homozygous, GG LL* gg ll

a). Homozygous gray, long * ebony, vestigial (GG LL* gg ll) ----> Gg Ll -----> F1

Cross between F1 have the progeny with the following genotypes (F2)

Gg Ll* Gg Ll -à G_L_ (9/16, gray, long), G_ ll (3/16, gray, vestigial), gg L_ (3/16, ebony, long), gg ll (1/16, ebony, vestigial)

b). Homozygous gray, vestigial * ebony, long (GG ll* gg LL) -----> Gg Ll à F1

Cross between F1 have the progeny with the following genotypes (F2)

Gg Ll* Gg Ll -à G_L_ (9/16, gray, long), G_ ll (3/16, gray, vestigial), gg L_ (3/16, ebony, long), gg ll (1/16, ebony, vestigial)

c). Homozygous gray, long * gray vestigial (GG LL* GG ll) --à GG Ll ---> F1

Cross between F1 have the progeny with the following genotypes (F2)

GG Ll* GG Ll -à GG L_ (3/4, gray, long), GG ll (1/4, gray, vestigial)