1. X-Linked Inheritance (Sex Linked)
genes are carried on chromosomes
this causes no difference for males and females for the first 22 chromosome pairs (autosomes)
the 23rd pair of chromosomes in humans however is the XX (female) and XY (male) chromosomes

2. Example: A male and a female have offspring
Example: A male and a female have offspring. What are their genotypes for sex? What is the likelihood of them having male or female offspring?

3. some genes are carried on the X chromosome(s)
this means females have one allele on each chromosome (two total)
whereas males only have one X chromosome, and therefore only one allele
males therefore can have a recessive allele and still display the phenotype

4. Example: Hemophilia is a disease in humans that causes blood to not clot properly. It shows up more often in males than females. The allele for hemophilia is present on the X chromosome. If a heterozygous female mates with an unaffected male, which of their offspring have hemophilia?

5. Example: Colorblindness is another disorder caused by a defective recessive allele on the X chromosome. If a color-blind male has a child with a carrier female, what percentage of the offspring will be colorblind?