sex-linked traits

Thomas Hunt Morgan

worked with D. melanogaster, found out eye color is X linked        

X-linked inheritance

trait is linked to the X chromosome

Y-linked inheritance

trait is linked to the Y chromosome

Dosage compensation

equalization of the amount of X-linked genes in males and females

Barr body

one X chromosome that is compacted and totally inactivated

Turner Syndrome

females with only one X chromosome

Klinefelter Syndrome

males with extra X chromosomes

Poly-X syndrome

females with more than two X chromosomes, more X’s = more likely to be intellectually disabled

How are X-linked traits inherited differently than Y-linked traits?

X linked traits can be female or male, y linked traits are male only

How did the Y chromosome evolve?

Mutation on one autosome caused maleness, and mutation of other genes reinforce male traits

What does the Xist RNA do?

Transcribed of the X that will be inactivated

Which X chromosome expresses the Xist RNA?

The inactive X chromosome