PLEASE EXPLAIN IN DETAIL. A male mouse that is heterozygous for a reciprocal tra

Question

PLEASE EXPLAIN IN DETAIL.

A male mouse that is heterozygous for a reciprocal translocation between the X chromosome and an autosome is crossed to a female mouse with a normal karyotype. The autosome involved in the translocation carries a gene responsible for coloration of the fur. The allele on the male's translocated autosome is wild-type, and the allele on its non-translocated autosome is mutant; however, because the wild-type allele is dominant to the mutant allele, the male's fur is wild-type (dark in color). The female mouse has light color in her fur because she is homozygous for the mutant allele of the color-determining gene. When the offspring of the cross are examined, all males have light fur, and all the females have patches of light and dark fur.

Select the correct genotype of the male parent:
T = translocated chromosome, N = normal chromosome, A = an autosome, X = X chromosome, Y = Y chromosome

Select one:

a. Xf+TY; AT Af N

b. Xf+YT; AT AfN

c. XfTY ; AT Af+N

d. Xf+NY ; AN Af T

e. none of the above

Select the correct genotype of the female parent with light fur:
T = translocated chromosome, N = normal chromosome, A = an autosome, X = X chromosome, Y = Y chromosome

Select one:

a. Xf+NXN; AN Af N

b. Xf+XT; AT AfN

c. XfTX N; AT Af+N

d. XNX N; AfN Af N

e. none of the above

What is the genotype of the viable female offspring?

Select one:

a. Xf+TXN ATAfN

b. XNXN AfNAf+N

c. Xf+NXT ATAfN

d. Xf+TXN AfTAN

e. none of the above

What is the genotype of the viable male offspring?

Select one:

a. XNY; AfNAfN

b. XNY; AfNAf+N

c. Xf+NY; ATAfN

d. XfTY; AfTAN

e. none of the above

Explanation / Answer

Answer:

1) Male parent has translocated X chromosome carrying wild type dominant fur color gene (Xf+T), normal Y chromosome, autosome with translocated gene (AT) and autosome with mutant recessive fur color gene (AfN). Thus, genetype is Xf+T; AT AfN and answer is (a).

2) Female parent has both the X chromosomes normal and is homozygous for recessive fur color alleles present on autosomes. Thus genotype is XNXN; AfN AfN and answer is (d).

3) Genotype of viable female offspring will be Xf+TXN; ATAfN, and the answer is (a), because one X chromosome from female parent is normal while another x chromosome from male parent is translocated with fur color gene.

4) Genotype of viable male offspring will be XNY; AfNAfN and the answer is (a).

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