Introns and exons play a vital role in RNA splicing, a process by which introns are eliminated and exons are concatenated.

RNA splicing is a fundamental step in gene expression, during which the precursor messenger RNA (pre-mRNA), the initial transcript of a gene, undergoes modifications to become mature messenger RNA (mRNA). This mature mRNA serves as a template for protein synthesis. Pre-mRNA consists of both exons, which are the coding sequences, and introns, which are non-coding sequences. The relationship between introns, exons, and RNA splicing is evident in the fact that introns are excised and exons are fused during this process.

The RNA splicing process commences with the formation of a spliceosome, a large complex composed of proteins and small nuclear RNAs (snRNAs). The spliceosome identifies specific sequences at the boundaries of introns and exons, known as splice sites. Once the spliceosome is assembled on the pre-mRNA, it cleaves the RNA at these splice sites, removes the introns, and subsequently ligates the exons. This results in the generation of a mature mRNA molecule that includes only the coding sequences.

The removal of introns and the joining of exons can be intricate. In certain instances, alternative combinations of exons may be connected through a process known as alternative splicing. This mechanism allows a single gene to generate multiple protein variants, depending on which exons are incorporated into the mature mRNA. This enhances the diversity of proteins produced from a single gene, significantly contributing to the complexity of higher organisms.

In summary, introns and exons are essential components of the RNA splicing process. Introns are removed while exons are joined to form a mature mRNA molecule, which is crucial for protein synthesis. This splicing process not only facilitates gene expression but also increases protein diversity through alternative splicing.