Transposon

related topics
{acid, form, water}
{specie, animal, plant}
{disease, patient, cell}
{math, number, function}
{@card@, make, design}
{work, book, publish}

Transposons are sequences of DNA that can move or transpose themselves to new positions within the genome of a single cell. The mechanism of transposition can be either "copy and paste" or "cut and paste". Transposition can create phenotypically significant mutations and alter the cell's genome size. Barbara McClintock's discovery of these jumping genes early in her career earned her a Nobel prize in 1983. [1]

Transposons make up a large fraction of the C-value of eukaryotic cells. Transposons are often considered "junk DNA". In Oxytricha, which has a unique genetic system, they play a critical role in its development.[2] Transposons are very useful to researchers as a means to alter DNA inside a living organism.

Contents

Types of transposons

Transposons are only one of several types of mobile genetic elements. Transposons themselves are assigned to one of two classes according to their mechanism of transposition, which can be described as either "copy and paste" (Class I) or "cut and paste" (Class II).

Class I: Retrotransposons: Retrotransposons copy themselves in two stages, first from DNA to RNA by transcription, then from RNA back to DNA by reverse transcription. The DNA copy is then inserted into the genome in a new position. Reverse transcription is catalyzed by a reverse transcriptase, which is often coded by the transposon itself. Retrotransposons behave very similarly to retroviruses, such as HIV.

There are three main subclasses of retrotransposons:

  • Viral: encode reverse transcriptase (to reverse transcribe RNA into DNA), have long terminal repeats (LTRs), similar to retroviruses
  • LINEs: encode reverse transcriptase, lack LTRs, transcribed by RNA polymerase II
  • Nonviral superfamily: do not code for reverse transcriptase, transcribed by RNA polymerase III

Full article ▸

related documents
Prophase
Bacterial conjugation
Gram-positive bacteria
Microsatellite
Serine
Polyvinylpyrrolidone
Hexose
Plasmolysis
Halotolerance
Fermium
Organic compound
Silicate
Strong acid
Biotite
Alkaline earth metal
Aldehyde
SH3 domain
Plagioclase
Synthetic radioisotope
Coordinate covalent bond
Aspartic acid
Cinnabar
Chloride
Chemical reaction
Butane
Messenger RNA
Einsteinium
Synthetic element
Hexokinase
Transmembrane receptor