Final answer:
Alternative RNA splicing allows a single gene to produce various protein isoforms, greatly expanding the diversity of proteins without increasing genome size. It is a common gene regulation mechanism in eukaryotes, with a large proportion of multi-exon genes in humans exhibiting this process, highlighting its role as a rule rather than an exception.
Step-by-step explanation:
Discovered in the 1970s, alternative RNA splicing is a fundamental process in which different combinations of exons are joined together to produce various mature mRNA molecules from a single gene. This biological mechanism enhances the diversity of proteins that can be synthesized, without increasing the size of the genome. An estimated 70 to 95 percent of multi-exon genes in humans undergo alternative splicing, demonstrating that it is more a rule than an exception in the regulation of gene expression in multicellular eukaryotes.
Alternative splicing can occur in various forms, but it always maintains the original 5'-3' order of the exons, ensuring the integrity of the coding sequence. This process allows a single gene to encode multiple protein isoforms, varying in different tissues or developmental stages. Such a regulatory mechanism provides cells with an economical way to produce a wide range of proteins without the necessity for a corresponding number of genes. Furthermore, alternative splicing contributes to genomic diversity and adaptability without increasing genomic size.
While some instances of alternative splicing are seemingly random, most are tightly regulated, ensuring that the appropriate protein forms are produced where and when they are needed. The control of alternative splicing thus serves as a critical aspect of gene expression and cellular function, showcasing the complexity and efficiency of eukaryotic gene regulation.