Which RNA type is most directly influenced by the presence of exons in its sequence?

The type of RNA most directly influenced by the presence of exons in its sequence is mature messenger RNA (mRNA). Exons are the coding regions of a gene that are present in the pre-mRNA transcript and are retained after the splicing process. During mRNA processing, introns (non-coding regions) are removed, and exons are joined together to form the final mature mRNA molecule. This mature mRNA then serves as the template for protein synthesis during translation.

In contrast, while ribosomal RNA, transfer RNA, and small interfering RNA have important roles in the cell, they are not affected by the presence of exons in the same direct manner. Ribosomal RNA forms the structural and functional core of ribosomes but does not undergo splicing related to exons. Transfer RNA plays a role in translating the message carried by mRNA into amino acids but is not composed of exons and introns itself. Small interfering RNA is typically involved in gene silencing and regulation but also does not rely on exon structure for its function. Thus, mature mRNA is the only type of RNA that is fundamentally shaped by the splicing of exons and is therefore most directly influenced by them.