Ch. 10.5: Sex-Linked Traits Genes located on the X or Y chromosome XX = Female; XY = Male Objectives: 1.Explain how sex-linked genes produce different inheritance patterns in males and females. 2.Explain why most sex-linked disorders are more common in males. Vocab: sex-linked gene

X vs. Y More genes on X Male karyotype Female karyotype X: more than just genes for sex traits.

Thomas Hunt Morgan & Fruit Flies Discovers sex-linked traits. Recessive white eyes more common in MALE fruit flies. Females have to be homozygous recessive to have white eyes. Males only need one recessive allele for trait.

Sex-linked genes affect MALES more than females. Females can be carriers X N X n Males will express trait with just one allele, X n Y. Females have to be homozygous recessive to express trait.

Sex-Linked Disorders  Color-blindness  Hemophelia  Baldness  Fragile X  Versions of Muscular Dystrophy These are recessive disorders. There are dominant disorders that are more prevalent in females.

Color-blindness

Hemophelia Prevents blood clots. Without clotting factors (proteins), you can bleed to death.