- Once the intros are removed and the mRNA returns to a form of continuous coding sequences in the 5'-3' direction
- Even if only one nucleotide of an intron were left in the processed mRNA, protein would non-functional because the ribosome would process the wrong codons
- Cellular machinery that splices pre-mRNAS uses data at the splice junctions to decide where to split and rejoin the mRNA; several "pathways" are used
- Introns are intervening sequences - not expressed in proteins
- Exons are retained in the mature mRNA molecules. – expressing sequence
- Some RNAs splice themselves, and they are called autocatalytic RNAs. This is called self-splicing.
- Splicesome: A complex where splicing occurs in. Made up of small nuclear RNAs (snRNAs), small nuclear ribonucleoproteins (snurps) and proteins.