Sex-linked Inheritance

Hemophilia is an X-linked recessive disorder (Xh) that is passed through generations and can be traced by using a pedigree. mc018-1.jpg What is the probability that a female child of Charles and Marie would suffer from hemophilia?

0 percent

Punnett squares are used to show possible combinations of alleles or to predict the probability of a trait occurring in offspring. Cats that have coats that are a patchwork of black and orange are called tortoiseshell cats, are typically female, and have genes that code for both black fur (Xo) and orange fur (XO) located on the X chromosomes. Y chromosomes do not code for color in tortoiseshell cats. A female cat that has only orange fur (XOXO) is crossed with a male cat that has only black fur (XoY). mc013-1.jpg How many of the offspring will exhibit tortoiseshell coloring?

2 in 4

Drosophila eye color is an X-linked trait. Red eye color is dominant, and white eye color is recessive. Which Punnett square shows the probability that 100 percent of offspring will have red eyes?

A mc007-1.jpg

How are sex-linked traits inherited?

Alleles are passed from the parents' sex chromosomes to the sex chromosomes in the offspring.

Which symbol is used to label a male that expresses a sex-linked disorder on a pedigree?

D

Duchenne muscular dystrophy is an X-linked recessive disorder. mc009-1.jpg What is the probability that a female offspring of the cross that is shown above would have a recessive allele for Duchenne muscular dystrophy disorder?

NOT 25 percent

Hemophilia is an X-linked recessive disorder. mc005-1.jpg What is the probability of having hemophilia for the cross that is shown in the Punnett square?

NOT 75 percent

Which allele combination represents a female who has a heterozygous sex-linked trait?

XRXr

Which is not considered a sex-linked trait?

purple flower color in pea plants

What is the purpose of using a pedigree?

to understand patterns of inheritance in organisms