Sex-linked Traits and Pedigrees Biology Genetics

Pedigree Chart that shows how a trait and the genes that control it are inherited within a family. Helps to determine the inheritance of some alleles and predict them in the offspring.

Pedigree video

Sex-Linked Traits Genetic linkage that has to do with X and Y chromosomes. Men = XY; therefore can inherit X or Y linked traits. Female = XX; therefore can only inherit X linked traits.

Sex-linked Traits Men have only one X chromosome. When an X-linked trait is inherited it will most likely be expressed in his phenotype because in most cases, there is no corresponding gene on the Y chromosome.

Sex-Linked Traits Women: A recessive allele on one X chromosome is often masked in their phenotype by a dominant normal allele on the other chromosome. This is why women are frequently carriers of X-linked traits but more rarely have them expressed in their phenotypes.

Inheritance of sex-linked traits video

Examples of Sex-Linked Traits Hemophilia: Low levels or complete absence of a blood protein essential for clotting. Was known as the Royal Disease carried by Great Britain’s Queen Victoria.

Examples of Sex-Linked Traits Color Blindness: Color blindness (color vision deficiency) is a condition in which certain colors cannot be distinguished, and is most commonly due to an inherited condition. Red/Green color blindness is by far the most common form, about 99%, and causes problems in distinguishing reds and greens.

Are you Color Blind?

Autosomal vs. Sex Autosomal Chromosomes: Refers to any of the chromosomes other than the sex-determining chromosomes (i.e., the X and Y) or the genes on these chromosomes.