Alternative splicing is =necessary for all polycistronic RNA transcripts. Rather, alternative splicing is a process in which different combinations of exons are joined together to create multiple mature mRNA transcripts from a single gene. This process allows for the production of different protein isoforms from the same gene, increasing the diversity of the proteome. Polycistronic RNA transcripts, on the other hand, are RNA molecules that contain multiple coding regions, each of which can be translated into a separate protein. While alternative splicing can occur in polycistronic RNA transcripts, it is not necessary for their function.