Karyotype

          Autosomal chromosomes

          Sex chromosome

Nondisjunction

          X chromosome

          Y chromosome

                    Barr body

X-linked traits

          Hemophilia

          Color blindness

Sex-influenced traits

          Male pattern baldness

Amniocentesis

Chorionic villus sampling   CVS

Screening eggs

          Preovulatory egg

Screening embryos

Color blindness is X-linked -- Possible Genotypes:

         X^BX^B = Female with normal color vision

         X^BX^b = Carrier female with normal color vision

         X^bX^b = Female who is color blind

         X^BY = Male with normal color vision

         X^bY = Male who is color blind

Sex-Influenced traits - Beards, Breasts, and Baldness

                       Males          Females

               BB = Normal         Normal

               Bb = Bald              Normal

               bb = Bald               Bald