1. Sex-Linked Traits

2. Sex-linked Genes Found on the sex chromosomes Male : XY Female : XX
Who determines the sex of the offspring, dad or mom?

3. The “Y” chromosome contains genes associated with male sex development, so females don’t need a “Y” chromosome.
The most important genes needed in both males and females must be located on the X since both males and females have an X chromosome.

4. **Can males be carriers of sex-linked traits located on the X chromosome?**
Why or why not?
We have a trick to help us remember!!
healthy dad, healthy daughter;
sick mom, sick son

5. Alleles for sex-linked traits are written as superscript to the right of an X if trait is found on the X chromosome: X X H= normal h = diseased trait (hemophilia) XHXh = XHXH = XhXh = XHY = XhY =
Hemophilia = excessive bleeding when injured because there is an abnormal allele that aids in blood clotting

6. Cross a female carrier for hemophilia with a male hemophiliac:
Genotype:
Phenotype:

7. Cross a female carrier with a male non hemophiliac:
Genotype:
Phenotype:

8. Cross a normal female with a balding male:
Genotype:
Phenotype: