Linkage

Linkage is a term used in genetics to describe the tendency of DNA sequences that are close together on a chromosome to be inherited together during the meiosis phase of sexual reproduction. Two genes that are located close to each other on the same chromosome are said to be linked.

History

The concept of linkage was first introduced by the British geneticist William Bateson and his colleagues Reginald Punnett and Edith Rebecca Saunders in 1905. They observed that certain traits in sweet peas seemed to be inherited together, which contradicted the independent assortment principle proposed by Gregor Mendel.

Linkage and Recombination

During meiosis, chromosomes can exchange genetic material in a process known as recombination. This can result in the shuffling of genes between the two chromosomes, which can lead to offspring with different combinations of traits than their parents. However, genes that are close together on the same chromosome are less likely to be separated by recombination, and are therefore said to be linked. The closer two genes are to each other, the more likely they are to be inherited together.

Linkage Map

A linkage map is a genetic map that shows the relative positions of genes on a chromosome based on their linkage. The distance between two genes on a linkage map is proportional to the frequency of recombination between them. This can be used to estimate the physical distance between the genes on the DNA molecule.

Linkage Disequilibrium

Linkage disequilibrium is a situation in which some combinations of alleles or genetic markers occur more or less frequently in a population than would be expected from a random formation of haplotypes from alleles based on their frequencies.

See Also

• Genetic recombination
• Genetic linkage
• Linkage disequilibrium
• Linkage map
• Chromosome
• Meiosis

References

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