Genetic Linkage

Linked Genes

Genes that are located on the same chromosome and tend to be inherited together.

Why are linked genes inherited together?

Alleles for linked genes are less likely to be separated during meiosis because they are physically close to each other on the same chromosome.

Crossing over

The exchange of genetic material between homologous chromosomes during meiosis I that can sometimes separate linked genes.

Example of linked genes

Traits like hair color and eye color, for example, blonde hair and blue eyes, may be inherited together due to gene linkage.

Sex-Linked Genes

Genes located on the sex chromosomes (X or Y), most commonly found on the X chromosome.

Linkage Map

A genetic map that shows the relative positions of genes on a chromosome based on how frequently they are inherited together.

Frequency of Crossing Over

The measure of how often two genes are inherited together versus how often they are separated due to crossing over.

Recombinant Frequencies

The percentage of gametes that have both genes from the same chromosome.

Key point about crossing over frequency

Genes that are very close together on the chromosome will have a low frequency of crossing over, while genes farther apart will have a higher chance.

Linkage map example

A linkage map for the X chromosome could show locations of genes like hemophilia A and G6PD deficiency that are close together.