The Xs and Ys of Genetics Sex Linked Genes The Xs and Ys of Genetics

Sex Linked Genes There are 23 pairs of chromosomes and one of those pairs are the sex chromosomes. There are either X chromosomes or Y chromosomes.

Sex Linked Genes These chromosomes not only carry the genes that determine male and female traits, but also those for some other characteristics as well. Genes that are carried by either sex chromosome (X or Y) are said to be SEX LINKED or X-LINKED

Males Men normally have an X and a Y combination of sex chromosomes. Since only men inherit the Y chromosome, they are the only ones that inherit Y-linked traits.

Females Women have 2 X chromosomes

X Linked Traits Men and Women can get the X-linked traits since both inherit X chromosomes.

Sex inheritance patterns for male and female children

X Chromosome Traits Men only have one X chromosome Therefore genes on that chromosome are expressed in the male phenotype, even if it is a recessive gene.

X-linked traits In humans, at least 120 genes are known to be X-linked. Genes for hemophilia, red-green color blindness, congenital night blindness, and Duchene muscular dystrophy

Hemophilia An X-linked genetically inherited recessive disease Can not clot their blood Severe bleeding from minor cuts Mostly in males

Red-Green Color Blindness X-linked Cannot perceive red and green in the same Most often afflicts males