Quizs Ch 15 Notes Part I Sex-Linkage

The inheritance pattern of hemophilia.

• Autosomal dominant disorder

• X-linked recessive disorder

• Autosomal recessive disorder

• Y-linked disorder

A gene on one of the sex chromosomes is called: ________.

• A SEX-LINKED gene

• A AUTOSOMAL gene

• A DOMINANT gene

• A RECESSIVE gene

Examples of X-linked conditions

• Color-blindness (c) is recessive to normal vision (C).

• Sickle cell anemia is caused by a dominant allele.

• Cystic fibrosis is an X-linked condition.

• Hemophilia (h) is recessive to being able to produce blood clotting factors (H).

If a son expresses an X-linked condition, who did he inherit it from?
Does this mean this parent also expresses the condition?

• His father, because he inherits the Y chromosome from him.

• His mother, because mothers contribute one of their X chromosomes to their sons.

• His grandfather, as traits can skip generations.

• His uncle, since traits can be inherited from relatives.

Hemophilia description

• A genetic disorder where the blood clotting process is defective.

• A condition that causes excessive blood clotting.

• An autoimmune disease affecting blood cells.

• A viral infection that leads to bleeding disorders.

Probability of having a daughter with hemophilia

• 0%

• 25%

• 50%

• 75%

Genes on the X versus Y chromosome

• The X chromosome carries different genes and more genes compared to the Y chromosome.

• The Y chromosome carries more genes than the X chromosome.

• Both X and Y chromosomes carry the same number of genes.

• The X chromosome is only responsible for male traits.

Probability that their first son will have hemophilia

• 25%

• 50%

• 75%

• 10%

A man without hemophilia and a woman who is a carrier for hemophilia have children.
Parent Genotypes?

• X^HY x X^HX^h

• X^HY x X^hX^h

• X^hY x X^HX^h

• X^HY x X^HX^H

X-linked gene inheritance in males and females

• Females have only one copy of the gene on the X chromosome, while males have two copies.

• Males inherit X-linked conditions more frequently due to having only one copy of the gene on the X chromosome.

• Both males and females inherit two copies of the gene on the X chromosome.

• Females are more likely to inherit recessive X-linked conditions than males.