In Drosophila two genes affecting body color are known. A mutant allele at one l
ID: 81169 • Letter: I
Question
In Drosophila two genes affecting body color are known. A mutant allele at one locus is a X-linked and prevents the formation of granules on which pigment is laid down. An absence of these. Another gene is an autosomal linked recessive, causes the color (the pigment involved) to be blood-red instead of normal color. True breeding albino males that were homozygous for normal body color are crossed to true-breeding blood-red females. Determine the genotypes and phenotypes of the F_1 generation and F_1 generation.Explanation / Answer
Answer:
Suppose:
Sex linked albino allele = Xa, Wild type = X
Blood red allele = r, Wild-type = R
Parent Crossing :
R/R; Xa/Y x r/r; X/X
Genotype and phenotype of F1:
Female phenotype
Female genotype
Male phenotype
Male genotype
Normal
R/r; Xa/X
Normal
R/r; X/Y
Genotype and phenotype of F2:
Female phenotype
Female genotype
Male phenotype
Male genotype
1/4 blood red,
3/4 normal
R/R; X/Xa
R/R; X/X
2 R/r; X/Xa
2 R/r; X/X
r/r; X/Xa
r/r; X/X
1/2 albino
3/8 normal
1/8 blood-red
R/R; Xa/Y
R/R;X/Y
2 R/r; Xa/Y
2 R/r; X/Y
r/r; Xa/Y
r/r; X/Y
Female phenotype
Female genotype
Male phenotype
Male genotype
Normal
R/r; Xa/X
Normal
R/r; X/Y