Transposon
Say it: tranz-POH-zon
A transposon is a DNA sequence that can move from one place in a genome to another, in some cases leaving a copy behind as it goes.
Also: transposons, transposable element, jumping gene
Definition
What is a transposon?
A transposon, or transposable element, is a stretch of DNA that can change its position within a genome. Barbara McClintock discovered these elements in the 1940s while studying maize, where their movement in and out of pigment genes produced speckled kernels, and she was awarded a Nobel Prize for the work in 1983. Transposons have since been found in almost every organism examined, and they and their decayed remains make up close to half of the human genome.
There are two main classes. DNA transposons move by cut and paste: an enzyme called transposase, often encoded by the element itself, cuts the sequence out and inserts it at a new site. Retrotransposons move by copy and paste: they are transcribed into RNA, which reverse transcriptase copies back into DNA that is then inserted elsewhere, so the original stays put. In humans, LINE-1 and Alu elements are the main families still active, although most copies can no longer move.
A transposon landing inside a gene can disrupt it, and new insertions have been linked to inherited diseases and some cancers. Over evolutionary time, however, transposons have supplied raw material for new genes and gene switches. In bacteria they often carry antibiotic-resistance genes, helping resistance spread.
Word parts
Where does the word “transposon” come from?
- transpos-
- to move across, to change the place ofLatin trans- (across) and ponere (to put), via French transposer
- -on
- a unit (scientific suffix)as in electron
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Terms that go with it
- GenomeA genome is the complete set of DNA in an organism or cell, including all of its genes and the stretches of DNA between them.
- Reverse transcriptaseReverse transcriptase is an enzyme that builds DNA from an RNA template, letting retroviruses such as HIV turn their RNA genome into DNA.
- MutationA mutation is a lasting change in an organism's DNA sequence, ranging from a single altered base to large rearrangements of chromosomes.
- Antibiotic resistanceAntibiotic resistance is the ability of bacteria to survive and multiply despite an antibiotic that once killed them or stopped their growth.
- RetrovirusA retrovirus is an RNA virus that copies its genome into DNA with reverse transcriptase and inserts that DNA into the host cell's chromosomes.
- PlasmidA plasmid is a small, usually circular DNA molecule that copies itself independently of the main chromosome, found mostly in bacteria.
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Checked against
Written for biofideX in plain words, after checking these references:
- NCBI MeSH: DNA Transposable Elements
- Bourque et al. (2018), Ten things you should know about transposable elements, Genome Biology
- The Nobel Prize in Physiology or Medicine 1983: Press release
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