Final answer:
Pre-mRNA splicing is facilitated by a complex called the spliceosome, which removes non-coding regions known as introns from the primary RNA transcript and joins the remaining exons.
Step-by-step explanation:
Pre-mRNA splicing requires the aid of a multi-component structure called the spliceosome. This complex process involves the precise removal of introns (non-coding regions) from a primary RNA transcript.
Spliceosomes are critical ribonucleoprotein complexes that facilitate this process. They are composed of proteins and RNA molecules called small nuclear RNAs (snRNAs).
The spliceosome recognizes sequences at the 5' and 3' ends of the intron. It then catalytically cuts the transcript at these points and ligates, or joins, the remaining exons together.
This results in a mature mRNA molecule, which then leaves the nucleus to direct protein synthesis in the cytoplasm.