Encyclopedia > Splicing

  Article Content

Splicing

In genetics, splicing is a modification of genetic information prior to translation.

In eukaryotes, a gene often contains altereing sequences known as exons and introns. In contrast to prokaryotes, which do not have introns, the primary mRNA transcript called pre-mRNA (see transcription) from the DNA has to be spliced, that means, the introns are removed form the mRNA in an intramolecular reaction[?], where the mRNA acts as a ribozyme, with the assistance of spliceosomes. The spliceosome also attaches new noncoding units:

  • A 5' cap, a guanine triphosphate nucleotide, thus named because it binds to the 5' end of the mRNA;
  • A leader that follows the 5' cap but precedes the exons;
  • A trailer that follows the exons;
  • A poly-A tail that follows the trailer.

Mutations in the introns can prevent splicing and thus protein biosynthesis. In many cases, the splicing process leads to several mRNA's. This phenomenon is called alternative splicing.

 XXXXEEEEIIIEEEEEEEEEEIIIIEEEEEEEEEEXXXX   DNA with exons and introns
            ↓transcription↓
     EEEEIIIEEEEEEEEEEIIIIEEEEEEEEEE       mRNA (primary transcript) with exons and introns
            ↓  splicing   ↓
     CLLLEEEEEEEEEEEEEEEEEEEEEEEETTTTAAAA  mRNA (spliced) with exons, 5' cap, leader, trailer and poly-A tail
            ↓ translation ↓
              polypeptide

See also : genetics -- cDNA



All Wikipedia text is available under the terms of the GNU Free Documentation License

 
  Search Encyclopedia

Search over one million articles, find something about almost anything!
 
 
  
  Featured Article
Grateful Dead

... Dead[?], both released in 1970. These records featured the band's laid-back acoustic musicianship and more traditional song structures. Jerry played lead guitar and ...

 
 
 
This page was created in 34.5 ms