In fruit flies, yellow body (y) is recessive to gray bod...

Question

In fruit flies, yellow body (y) is recessive to gray body , and the trait of body color is inherited on the X chromosome. Vestigial wing (v) is recessive to full-sized wing (v⁺), and the trait has autosomal inheritance. A cross of a male with yellow body and full wings to a female with gray body and full wings is made. Based on an analysis of the progeny of the cross shown below, determine the genotypes of parental and progeny flies.
[Table below appears at this point containing crosses and results]
Phenotype Number of Number of
Males Females _
Yellow body, full wing 296 301
Yellow body, vestigial wing 101 98
Gray body, full wing 302 298
Gray body, vestigial wing 101 103 _
800 800

Accepted Answer

Hi, everyone. Let's take a look at this practice problem together. The gene that controls the color of the body in Joseph is located on the X chromosome. The wild type recessive A lil produces a yellowish brown body color. While the mutant Ebony A lil produces a gray body color. A male Joola with a gray body mates with a female Drosophila with a yellowish brown body. What proportion of their female offspring would be expected to have a yellowish brown body color. The answer options are a zero B 25% C and D 100%. So we are talking about a color gene that is located on the X chromosome andro Sophal and there is the wild type recessive a little, let's represent that a little by using lower case B that a little produces a yellowish brown body color. Now, the mutant ebony A lil produces the gray color. So let's represent that by using capital B. So lowercase B equals the yellowish brown color and capital B equals the gray color. Now, let's determine the genotypes of our parent Drosophila. So a gray male Joola would have what genotype? Well, the chromosomes would be 1 x and 1 y. But the ally for the X chromosome would be the capital B for the yellowish brown female. The two chromosomes are both X. But what are the ails? Remember? Yellowish brown is the recessive wild type. Therefore, each of the ailes would be lowercase B, lowercase B. So to determine the female offspring that would have a yellowish brown body color, we use a punt square and fill it out. And that completed puit square is on the screen. The male alleles and chromosomes are in the top row. So X capital B N Y and the female alleles and chromosomes are in the top in the first column, X lowercase B X lowercase B. If we analyze the pun square, there are two female offspring. However, they do not have both of the ails recessive. And remember that wild type A lil that produces the yellowish brown body is recessive. Therefore, they need two recessive wild type ails and neither of the female offspring does. Therefore, the correct answer is option a 0%. All right, everyone. I hope you found this helpful and I'll see you soon for the next practice problem.

Key Concepts

X-Linked Inheritance

Autosomal Inheritance

Punnett Square Analysis

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