Question

Are exons removed?

Answer 1

Exons:

1. In eukaryotes, the DNA segments contain exons and introns. The coding sequences are known as ‘exons’ which are interrupted by non-coding sequences called ‘introns’.
2. Exons contain nucleotide sequences (genetic code) that are translated into proteins.
3. Introns are the non-coding sequences present between two exons.
4. During the processing of pre-mRNA, introns are removed since they are non-functional and exons are spliced together. This process is known as ‘splicing’.
5. Splicing is facilitated by a large ribonucleoprotein complex called ‘spliceosome’. It consists of small nuclear RNAs (U1, U2, U4, U5, U6) and additional proteins.
6. Exons are not removed. Exons are joined during splicing.