Genetic linkage

Genetic linkage is a fundamental concept in the field of genetics. It refers to the tendency of DNA sequences that are close together on a chromosome to be inherited together during the meiosis phase of sexual reproduction.

Overview

Two genes that are located close to each other on the same chromosome are said to be linked. These genes often tend to be inherited together, as they are located on the same DNA molecule. The closer two genes are to each other, the less likely it is that they will be separated during chromosomal crossover, a process that occurs during meiosis.

History

The concept of genetic linkage was first introduced by the British geneticists William Bateson and Reginald Punnett shortly after the rediscovery of Mendelian inheritance at the turn of the 20th century. They noticed that certain traits tend to be inherited together, which was not expected according to Mendel's independent assortment principle. This led to the discovery of genetic linkage.

Linkage Maps

A linkage map is a genetic map that shows the relative positions of genes on a chromosome. The distance between genes is measured in centimorgans (cM), which is a unit of recombinant frequency. One cM is equivalent to a 1% chance that a marker at one genetic locus will be separated from a marker at a second locus due to crossover in a single generation.

Genetic Recombination

Genetic recombination is the process by which a strand of genetic material (usually DNA, but can also be RNA) is broken and then joined to a different DNA molecule. In eukaryotes, recombination commonly occurs during meiosis as chromosomal crossover between paired chromosomes. This recombination results in offspring having different combinations of genes from those of their parents, and can produce new combinations of alleles.

See Also

• Chromosome
• DNA
• Gene
• Meiosis
• Genetic recombination
• Linkage map
• Centimorgan
• William Bateson
• Reginald Punnett

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