Linkage

Linkage: The proximity of two or more genes on a chromosome, which tends to cause them to be inherited together.

Linked genes are genes found on the same chromosomes.

Linkage group: two or more genes on a chromosome that tend to be inherited as a group.

Linked genes are inherited together and therefore do not segregate during meiosis. They are therefore transmitted into the same gamete.

Sex-linked genes

Are genes located on the sex chromosomes.

Most sex-linked genes are carried on the X chromosome whereas the Y chromosome carries very few genes and is almost empty.

Sex linked genes on the Y chromosomes include;

• Premature baldness.
• Hairy pinna and nose

Sex linked genes on the X chromosomes include;

• Colour blindness
• Haemophilia

These characteristics can arise in either male or females.