Navigation Links
Intron


Introns are sections of DNA within a gene that do not encode part of the protein that the gene produces, and are spliced out of the mRNA that is transcribed from the gene before it is exported from the cell nucleus. Introns exist mainly (but not only) in eukaryotic cells. The regions of a gene that remain in the spliced mRNA are called exons.

Introns sometimes allow for alternative splicing of a gene, so that several different proteins that share some sections in common can be produced from a single gene. The control of mRNA splicing, and hence of which alternative is produced, is performed by a wide variety of signal molecules. Introns also sometimes contain "old code," sections of a gene that were probably once translated into protein but which are now discarded.

Some introns such as Group I and Group II introns are actually ribozymes that are capable of catalyzing their own splicing out of the primary RNA transcript. They remove themselves on their own.

The amount of intron DNA varies widely between species. The pufferfish species Fugu rubripes has a very low amount of intron DNA, whereas related species have higher amounts. Introns are not to be confused with junk DNA, which is all DNA without known function that is not part of a gene.

Intron evolution

There are two competing theories as to the evolutionary origin of introns, which is usually studied in a highly conserved family of genes such as the actins. In the introns-early model ancestral genes are believed to have included a large number of introns, some of which have been lost over evolutionary time, leading to the different but similar intron patterns in related genes of different species. The introns-late model suggests instead that introns occur in the same location in variants of a given gene because the location is in some way predisposed to the introduction of an intron, and therefore that a similar intron pattern may arise in two different species by a form of convergent evolution.

See also

Reference

  1. Walter Gilbert (1978 Feb 9) "Why Genes In Pieces?" Nature 271 (5645):501.


'"/>


(Date:9/16/2014)... at the Columbia Center for Children,s Environmental Health at ... to demonstrate an association between childhood asthma and prenatal ... of household products. Results appear online in the journal ... to mothers exposed during pregnancy to higher levels of ... had a 72 percent and 78 percent increase in ...
(Date:9/16/2014)... Hopkins neuroscientists have discovered the "molecular brakes" that time ... cochleas of mice. These "hair cells" translate sound waves ... and are interpreted as sounds. If the arrangement of ... A summary of the research will be published in ... , "The proteins Hey1 and Hey2 act as brakes ...
(Date:9/16/2014)... EUGENE, Ore. -- Each tree species has its own ... researchers and colleagues from other institutions who studied the ... growing on a Panamanian island. , "This study demonstrates ... plant families and with different ecological strategies possess very ... Steven W. Kembel, a former postdoctoral researcher in the ...
Breaking Biology News(10 mins):Phthalates heighten risk for childhood asthma 2Phthalates heighten risk for childhood asthma 3Hey1 and Hey2 ensure inner ear 'hair cells' are made at the right time, in the right place 2Microbiome research shows each tree species has a unique bacterial identity 2
... be difficult for a terrorist to obtain genes from the ... Armed with a fake email address, a would-be bioterrorist could ... online, and receive them by post within weeks. , That's ... the bioterror risks posed by the booming business of gene ...
... students have discovered the antler of an Irish Elk in cliffs ... the exact age of the antler has yet to be determined, ... lived around 11,000 years ago. The giant deer roamed the open ... of the last Ice Age, as the glaciers retreated northwards. ...
... Medical Institute researchers have discovered that pheromones essential for ... and not by the vomeronasal system, as researchers had ... epithelium, which was presumed to be mostly involved with ... pheromone detection. , Howard Hughes Medical Institute investigator ...
Cached Biology News:The bioweapon is in the post 2The bioweapon is in the post 3The bioweapon is in the post 4Students discover 11,000 year old remains of Irish Elk 2Olfactory system detects pheromones that control reproduction 2Olfactory system detects pheromones that control reproduction 3Olfactory system detects pheromones that control reproduction 4
Other biology definitionOther Tags