Home > Splicing (genetics)

In eukaryotes, a gene often contains altering 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 from 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 tri phosphate 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 biosynthesisnucleus of the cell light blue , genes (DNA, dark blue are transcribed into RNA. This RNA is then subject to post-transcriptional modification and control, resulting in a mature mRNA red that is then transported out of the nucleus and into the cytoplasm p.

In many cases, the splicing process leads to several mRNA's. This phenomenon is called alternative splicingAlternative splicing is the process that occurs in eukaryotes in which the splicing process of a pre-mRNA can lead to different ripe mRNA molecules and therefore to different proteins. Also viruses have adapted to this biochemical process when using the p.

See also : genetics -- cDNA