Sex-Linked Traits Boy or Girl? The Y Chromosome “Decides” Y chromosome

What are Sex Linked Traits? In 1910, Thomas Morgan discovered traits linked to sex chromosomes in fruit flies. Some genes are attached to the X and Y chromosomes EXAMPLE: In humans, colorblindness and hemophilia are found on the X chromosomes

What are Sex Linked Traits? In Men, traits expressed anytime even one allele is present In Women, must have two alleles to show trait Children inherit color blindness from their mothers

Punnett Square: What sex will the offspring be? 50% chance of a male or a female child.

Hemophilia is carried by the mother Phenotype: 25% hemophiliac males 25% carrier females 25% normal males 25% non-carrier, non-hemophiliac females

If Dad is color blind, will you be color blind? Phenotype: 0% color blind males 100% color blindness carrier females

What if Mom is color blind? Phenotype: 100% carrier females 100% color blind males