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Transposons are sequences of DNA that can move around to different positions within the genome of a single cell, a process called Transposition. In the process, they can cause mutations, and change the amount of DNA in the genome. Transposons are also called "jumping genes" or "transposable genetic elements". Transposons can move directly from one position to another within the genome, while retrotransposons have first to be transcribed to RNA and then back to DNA by reverse transcriptase. Transposons are very useful to researchers as a means to alter DNA inside of a living organism.1 Mechanism
A transposon needs the enzyme transposase , which is often encoded by the transposon itself. The ends of the transposon sequence consist of inverted repeats (identical sequences reading in opposite directions). The transposase binds to both the inverted repeats of the transposon and the target site on the genome, where the transposon will move to. This target site is cut, leaving sticky ends. The transposon is then ligated into the target site, the gaps are filled in, resulting in direct repeat s.
2 Examples
- The first transposons were discovered in maize (Zea mays), (aka corn) by Barbara McClintock in 1940, for which she was awarded a Nobel PrizeThe Nobel Prizes (pronounced no-BELL or no-bell are awarded annually to people who have done outstanding research, invented groundbreaking techniques or equipment, or made outstanding contributions to society. It is generally regarded as the supreme comme in 1983Events January January 1 Beat Raaflaub became Basel Boys Choir's new conductor January 1 the ARPANET officially changes to use the Internet Protocol, creating the Internet. January 1 compulsory wearing of seat belts becomes law in the UK. January 2 The mu. She noticed insertion s, deletions, and translocation s, caused by these transposons. These changes in the genome could, for example, lead to a change in the colour of corn kernels. About 50% of the total genome of maize consists of transposons.
- Transposons in DrosophilaDrosophila melanogaster Drosophila subobscura Drosophila ( Greek , drosos " dew", + phila "loving") is a genus of fruit fly however, members of Drosophila are more appropriately termed vinegar flies, wine flies, pomace flies, grape flies, and picked fruit (the fruit fly) are called P element s. They seem to have first appeared in Drosophila melanogasterDrosophila melanogaster Black-bellied Dew-lover a dipteran (two-winged) insect, is the species of fruit fly that is commonly used in genetic experiments. The life cycle of Drosophila melanogaster at 25 °C takes only 2 weeks. Females lay eggs (embryos) tha only about 50 years ago. Since then, they have spread through every populationFor the use of the word population in statistics, see statistical population. In the most common sense of the word, a population is the collection of people—or organisms of a particular species—living in a given geographic area. Populations are studied in of the speciesThis article discusses biological species. Also see combinatorial species for the mathematical meaning of the term. Species is also a movie by Roger Donaldson. In English "species" is both singular and plural. The word " specie" is unrelated and is used t. Artificial P elements can be used to insert genes into Drosophila by injecting the embryo.
- Transposons in bacteria usually carry an additional gene for a function other than transposase, often an antibiotic resistance. In bacteria, transposons can jump from the "regular" DNA to plasmids and back, allowing the transfer and permanent addition of, for example, antibiotic resistance, leading to multiresistant strain s.
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