BRAINCAKERNA Splicing
In eukaryotes, genes contain exons (coding sequences) separated by introns (non-coding sequences). When a gene is transcribed, the whole sequence, introns and exons, is copied to make pre-mRNA.
Before the mRNA can be translated, the introns must be removed. This is called RNA splicing. It takes place in the nucleus and is carried out by spliceosomes, complexes of proteins and small RNA molecules. The spliceosome recognises the boundaries of each intron, cuts it out and joins the exons together to form mature mRNA. The mature mRNA then leaves the nucleus.
Prokaryotic genes do not contain introns, so bacterial mRNA is not spliced.
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More in Gene Expression
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All 39 lessons in Gene Expression · All Edexcel A-level Biology topics