Transposon

Transposons are genes that can move. They have a specific target site,allowing them to move or 'jump' into different DNA sites^[1]. Transposons leave copies of themselves wherever they stop. Half of the human genome consists of these 'jumping genes'^[2]. They are important for genomic variation and evolution in organisms. Transposons are subdivided into 2 classes:

• Class I transposons - also called retrotransposons - they make up 40% of the human genome. They move from one genome to another via a 'copy and paste' mechanism in which an RNA intermediate is transcribed from the retrotransposon, then made into cDNA via reverse transcriptase where it binds to the recipient DNA. The original genomic region containing the retrotransposon is not deleted.
• Class II transposons - move from one genome to another via a 'cut and paste' mechanism^[3]. The mechanism is to produce the enzyme protein transposase which will cleave DNA in a staggered sticky end cut. DNA polymerase will then re-attach the transposon to another place in the genome^[4].

References

1. ↑ Bruce Alberts,Alexander Johnson,Julian Lewis,Martin Raff,Keith Roberts and Peter Walter (2002) Molecular Biology Of The Cell,4th edition,New York: Garland Science.p287
2. ↑ Hardin, J. Bertoni, G. Kleinsmith, L (2012). Becker's World of the Cell. 8th ed. San Francisco: Pearson: 527
3. ↑ Kimball’s Biology Pages. Transposons: Mobile DNA. 2018 [cited 15/11/18]; Available From: http://www.biology-pages.info/T/Transposons.html
4. ↑ Scitable. Transponsons: The Jumping Genes. 2014 [cited 09/12/2018]; fckLRAvailable from: https://www.nature.com/scitable/topicpage/transposons-the-jumping-genes-518