Splicing
In eukaryotes, pre-mRNA or primary transcripts need to undergo some modifications before the mRNA sequence is functional for translation. One of the modifications is RNA Splicing. The splicing process is done by a complex of small proteins and smll nuclear RNAs (snRNAs) called 'spliceosomes'.
Splicing involves the removal of noncoding sequences, 'introns', that interrupt the coding sequence of the gene. Length of these 'introns' vary between a single nucleotide to 10,000 nucleotide bases. Once the 'introns' are removed, the remaining cluster of sequences are attached together, forming a complete mRNA that is now a functional gene sequence.
Alternative Splicing
- Splicing can be done differently. For example, some 'introns' may be removed and the 'exons' rearranged before joining together. This gives rise to different translation products for one fragment of pre-mRNA.[1]
Reference
- ↑ Alberts, B; Bray, D; Hopkin,K; Johnson, A.; Lewis,J; Raff,M; Roberts,K; Walter,P (2014) Essential Cell Biology, 4th edn., p232-236 New York: Garland Science.