SEX- LINKED TRAITS an inherited trait that has a gene on the x chromosome but no corresponding gene on the y chromosome (genes that only exist only on the sex chromosomes)
Examples of human sex-linked traits Hemophilia Red-green color blindness Muscular dystrophy Male pattern baldness
Inherited Disorders inherited disorders - an abnormal trait passed on through genes examples: red-green colorblindness, some handicaps
How to work sex-linked trait problems Hemophilia: is a rare, inherited bleeding disorder in which your blood doesn’t clot normally. If you have hemophilia, you may bleed for a longer time than others after an injury. You also may bleed internally, especially in your knees, ankles, and elbows. This bleeding can damage your organs or tissues and, sometimes, be fatal.
All possible genotypes & phenotypes: genotypes phenotypes XHXHXHXhXhXhXHYXhYXHXHXHXhXhXhXHYXhY Normal female Female carrier Female hemophiliac Normal male Male hemophiliac
What is a carrier? carrier - expresses the normal characteristic but has both dominant and recessive genes (have the gene for a trait but do not express the trait themselves) for sex-linked traits, males cannot be carriers XHXhXHXh
How to work sex-linked trait problems: start with this type of punnett square X X Y Y X X X
How to work sex-linked trait problems: put the genes on the X chromosome X X Y Y X X X Cross a normal husband with a carrier wife H H h HH H Hh h