Retrotransposon: Difference between revisions
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== Retrotransposon == | |||
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File:Retrotransposons.png|Retrotransposons | |||
File:LINE1s_and_SINEs.png|LINE1s and SINEs | |||
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Latest revision as of 00:36, 27 February 2025
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[edit]
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[edit]
Retrotransposons are categorized into two types: LTR (Long Terminal Repeat) retrotransposons and non-LTR retrotransposons.
LTR Retrotransposons[edit]
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[edit]
Non-LTR retrotransposons can be further divided into two main types: LINEs (Long Interspersed Nuclear Elements) and SINEs (Short Interspersed Nuclear Elements).
LINEs[edit]
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[edit]
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.
