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Alu element

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noun, plural: Alu elements

A transposable element made up of short stretch of DNA whose sole function is to self-reproduce and thus sometimes referred to as selfish or parasitic gene


The repeated sequences occur as multiple copies of nucleic acids in the genome. These repeats may involve the DNA or the RNA. There are three major types of repeated sequences: (1) terminal repeats, (2) tandem repeats, and (3) interspersed repeats. Interspersed repeats are repeated sequences where the copies are nonadjacent and dispersed throughout the genome. Examples of interspersed repeats are Alu elements and long interspersed nuclear elements (or LINEs).

Alu elements are interspersed repeats that are made up of a short stretch of DNA as opposed to LINEs that are relatively longer. Apart from that, they also differ in function. Alu elements are specialized for uncoupling intrachromosomal gene conversion whereas LINEs are involved in uncoupling interchromosomal genes. Both of them though are essential in allowing genes to evolve by uncoupling the gene conversion network thereby promoting evolution and the development of new species.

Alu elements derived their name from the characterization of the action of the Arthrobacter luteus restriction endonuclease. Similar to LINEs, Alu elements are also transposable elements (particularly, retrotransposons). They are mobile genes that are copied and inserted into the genome but at a different site in the genome.

See also: