Question

1. You are tracking two genes in drosophila (body color and eye color). To determine whether the traits are on the same chromosome you set-up the following cross: Orange body & Red eyes (w+/w;b+/b) x White body & Brown eyes (w/w;b/b) Predict the phenotype ratios of the offspring if the genes are on two different chromosomes (include the phenotypes). Show how you determined this.

Answer 1

Answer:

Phenotypic ratio:

In this cross among 16 offsprings,

4 offspring phenotypically produced (w+wb+b) Orange body & Red eyes

4 offspring phenotypically produced (w+wbb) Orange body & Brown eyes

4 offspring phenotypically produced (wwb+b) White body & Red eyes

4 offspring phenotypically produced (wwbb) White body & Brown eyes

Proportion is: 4 : 4 : 4 : 4

Step-by-step explanation:

Orange body & Red eyes (w+/w;b+/b) x White body & Brown eyes (w/w;b/b)

w+wb+b × wwbb-----------(1)

Chromosomes become half and alleles become separated. Gametes produced from each organism due to meiosis are shown below.

w+b+, w+b, wb+ and wb × wb, wb, wb and wb--------------(2)

Mating of these alleles are represented below in the form of checkerboard.

w+b+ w+b wb+ wb

wb w+wb+b w+wbb wwb+b wwbb

wb w+wb+b w+wbb wwb+b wwbb

wb w+wb+b w+wbb wwb+b wwbb

wb w+wb+b w+wbb wwb+b wwbb

Answer

Phenotypic ratio

In this cross among 16 offsprings,

4 offspring phenotypically produced (w+wb+b) Orange body & Red eyes

4 offspring phenotypically produced (w+wbb) Orange body & Brown eyes

4 offspring phenotypically produced (wwb+b) White body & Red eyes

4 offspring phenotypically produced (wwbb) White body & Brown eyes

Proportion is: 4 : 4 : 4 : 4