Why are exons kept to make mature mrna?

Exons are retained in mature mRNA because they contain the coding sequences that are essential for protein synthesis. During RNA splicing, introns (non-coding sequences) are removed, and exons are joined together to form a continuous coding sequence. This process ensures that the final mRNA molecule can be efficiently translated into a functional protein. Additionally, the presence of exons allows for alternative splicing, which increases the diversity of proteins that can be produced from a single gene.