1. Sex Linked Genes

2. Sex Chromosomes:
X and Y
Genotypes:
XX and XY
Some genes are absent from the Y chromosome.
Phenotypes:
Female and Male

3. Sex is determined by the combination of X and Y Chromosomes XX x XY
Genotypes:
XX and XY
Phenotypes:
Female, Male X XX XX Y XY XY

4. Carrier - An individual that has one copy of a recessive allele that causes a genetic disease in individuals that are homozygous for this allele.
Female Carriers are heterozygous for X-linked recessive disorders.
Sex Linkage - Genes associated with the X or Y chromosome. Most are found on the X Chromosome.

5. XB Xb XB XBXB XBXb Y XBY XbY
Color Blindness: Carried on the X chromosome (Xb)
Carrier Female XBXb crossed with Normal Male XBY XB Xb
Genotypes:
XBXB and XBY
XBXb and XbY
Phenotypes:
Normal Female
Normal Male
Carrier Female
Colorblind Male XB
XBXB
XBXb Y
XBY
XbY

6. XB Xb Xb XBXb XbXb Y XBY XbY
How can a Female inherit a Sex Linked disorder?
Carrier Female XBXb crossed with Colorblind Male XbY XB Xb
Genotypes:
XBXb and XBY
XbXb and XbY
Phenotypes:
Carrier Female
Normal Male
Colorblind Female
Colorblind Male Xb
XBXb
XbXb Y
XBY
XbY

8. XH Xh XH XHXH XHXh Y XHY XhY
Hemophilia: Carried on the X chromosome (Xh)
Carrier Female XHXh crossed with Normal Male XHY XH Xh
Genotypes:
XHXH and XHY
XHXh and XhY
Phenotypes:
Normal Female
Normal Male
Carrier Female
Hemophilia Male XH
XHXH
XHXh Y
XHY
XhY