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			== Retrotransposon ==
			<gallery>
			File:Retrotransposons.png\|Retrotransposons
			File:LINE1s_and_SINEs.png\|LINE1s and SINEs
			</gallery>

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'''Retrotransposon''' is a type of [[transposable element]] that can amplify itself in a genome and are ubiquitous components of the DNA of many [[eukaryotic]] organisms. They are a subclass of transposons. They are particularly abundant in plants, where they are often a major component of [[nuclear DNA]]. In maize, 49–78% of the genome is made up of retrotransposons. In wheat, about 90% of the genome is composed of repeated sequences such as retrotransposons. In mammals, nearly half the genome (45%) is composed of retrotransposons. Retrotransposons are also known as "Class I" transposons, due to their mechanism of transposition, which involves reverse transcription of the element's RNA transcript into DNA by a reverse transcriptase enzyme.

==Etymology==
The term "retrotransposon" was derived from the Latin word "retro", meaning backwards, and "transposon", which is a segment of DNA that can move to different positions within a genome.

==Types of Retrotransposons==
Retrotransposons are categorized into two types: LTR (Long Terminal Repeat) retrotransposons and non-LTR retrotransposons.

===LTR Retrotransposons===
LTR retrotransposons have direct repeats at both ends that play a role in transposition. The name "LTR retrotransposon" comes from the characteristic structure of these sequences, which are long terminal repeats (LTRs) at both ends.

===Non-LTR Retrotransposons===
Non-LTR retrotransposons can be further divided into two main types: LINEs (Long Interspersed Nuclear Elements) and SINEs (Short Interspersed Nuclear Elements).

====LINEs====
[[LINEs]] are long DNA sequences that are transcribed into RNA, reverse transcribed into DNA, and then inserted at a new site in the genome. They are typically 6,000-8,000 base pairs long.

====SINEs====
[[SINEs]] are short DNA sequences that are also transcribed into RNA, reverse transcribed into DNA, and then inserted at a new site in the genome. They are typically 100-400 base pairs long.

==Related Terms==
* [[Transposon]]
* [[Eukaryotic]]
* [[Nuclear DNA]]
* [[Reverse Transcriptase]]

[[Category:Genetics]]
[[Category:Molecular Biology]]
[[Category:DNA]]

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Retrotransposon - Revision history

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