Download Sex Linked Trait (X

Sex Linked Trait (X-Linked)
Hemophilia, a blood disease in which the blood does not clot, is a sex-linked trait. The recessive trait for
hemophilia is located on X chromosomes. Hemophilia occurs in males when an X chromosome carrying
the trait is paired with a Y chromosome. When an X chromosome carrying the trait is paired with an X
chromosome not carrying the trait, the female is a “carrier” and does not express (or show) hemophilia.
Simply stated: XX=female normal
XY=male normal
h
h
h
XX =female carrier
X X =female with disorder
h
X Y=male with disorder no other X to protect affected X
1. Create a Punnett Square to determine the possible genotypes and phenotypes of offspring produced
from the cross between a normal male and a carrier female. Hint: use the letter h to represent the
recessive trait for hemophilia. XX=female. XY=male
A. Can a normal male and a carrier female produce hemophilic children? If so, what sex would
they be? Male, Female, or Both?_______________________
B. Can a normal male and a carrier female produce children who are carriers of hemophilia but
are not actually hemophilic? If so, what sex would they be? Male, Female, or
Both?_________________________________________________
C. Can a normal male and a carrier female produce children who are neither carriers nor
hemophiliacs? If so, what sex would they be? Male, Female, or
Both?___________________________________________________________
2. Is it possible for a normal male and a normal female to produce a hemophilic child?
Is it possible for a normal male and a normal female to produce a carrier child?
Create a Punnett Square to determine your answers.
3. Can a hemophilic male and a normal female have hemophilic children?
Could they have children who are carriers?
Create a Punnett Square to determine your answers.