How are introns and exons related to RNA splicing?

Introns and exons are related to RNA splicing as introns are removed and exons are joined together during this process.

RNA splicing is a crucial step in the process of gene expression, where the pre-mRNA, the initial transcript of a gene, is modified to become mature mRNA. This mature mRNA is then used as a template for protein synthesis. The pre-mRNA is composed of both exons, which are the coding sequences, and introns, which are non-coding sequences. The relationship between introns and exons and RNA splicing lies in the fact that during RNA splicing, the introns are removed and the exons are joined together.

The process of RNA splicing begins with the assembly of a spliceosome, a large complex made up of proteins and small nuclear RNAs (snRNAs). The spliceosome recognises specific sequences at the intron-exon boundaries, known as splice sites. Once the spliceosome is assembled on the pre-mRNA, it cuts at the splice sites, removes the intron, and then joins the exons together. This results in a mature mRNA molecule that only contains the coding sequences, or exons.

The removal of introns and joining of exons is not always a straightforward process. In some cases, different combinations of exons can be joined together in a process known as alternative splicing. This allows for a single gene to produce multiple different proteins, depending on which exons are included in the mature mRNA. This increases the diversity of proteins that can be produced by a single gene and is a key factor in the complexity of higher organisms.

In summary, introns and exons are integral to the process of RNA splicing. The introns are removed and the exons are joined together to produce a mature mRNA molecule that can be used for protein synthesis. This process is crucial for gene expression and can also contribute to protein diversity through alternative splicing.