Sex-linked traits are so called because the genes for these traits are carried o

Question

Sex-linked traits are so called because the genes for these traits are carried on the sex chromosomes. Females have two X chromosomes, so for all X-linked traits, females can either be homozygous or heterozygous. Females do not have Y-linked traits. Males have one X and one Y chromosome. They are hemizygous (have one copy) of all X and all Y traits. The allele that they have for all X and Y traits will be the phenotypes displayed. Because of this, sex-linked traits display different inheritance patterns in males and females. Color blindness is an X-linked recessive trait. (Hint: to do this question, keep the allele associated with the chromosome ~ XD, Xd, Y, for example).

a. What is the genotype of a colorblind male? What is the probability that his sons will receive his bad allele? What is the probability that his daughters will receive his bad allele?

b. What is the genotype of a colorblind female? What is the probability that her sons will receive bad allele from her? What is the probability that her daughters will receive a bad allele from her?

c. Whatistheprobabilityofamalebeingheterozygousforcolorblindness?

d. What is the chance for a colorblind child if the mother is colorblind and the father is not? Report the chances for each sex separately! e. If a female is colorblind, what are the possible genotypes of her mother and father?

Explanation / Answer

Answer:

a). The genotype of a colorblind male: XdY

No sons will get bad allele from his father. All (100%) daughters will get bad allele from father. Because, X-chromosome of father will be transferred to his daughters only but not to his sons.

b). The genotype of a colorblind female: XdXd

The probability that her sons will receive bad allele from her: 100%

The probability that her daughters will receive a bad allele from her: 100%

Daughters will receive one X-chromosome from son and another X-chromsome from the mother. So all daughters will receive one bad allele from her mother. All sons will get X-chromsomes from his mother only.

c). the probability of a male being heterozygous for colorblindness; 50%

Homozygous for normal: 25%

Heterozygous for colorblindness; 50%

Homozygous for colorblindness; 25%

d). The chance for a colorblind child if the mother is colorblind and the father is not= 50% (All sons only are colorblind, but not daughters)

XdXd (colorblind mother) x XDY (normal father) ------Parents

e).

The colorblind female father always should be colorblind, and his genotype is : XdY

The colorblind female mothe should be either heterozygous fro color blind or completely colorblind, and their genotypes are : XDXd (50%) & XdXd (50%)

Related Questions

Navigate

• Browse (All)
• Browse S
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.