Final answer:
During pre-mRNA splicing in eukaryotes, introns are spliced out and exons are joined together to form the mature mRNA.
Step-by-step explanation:
During pre-mRNA splicing in eukaryotes, introns are spliced out and exons are joined together to form the mature mRNA.
Splicing is a process that removes the non-coding introns from the pre-mRNA and connects the coding exons to create the mature mRNA. This process is catalyzed by spliceosomes, which are protein complexes composed of proteins and RNA molecules called snRNAs. Spliceosomes recognize specific sequences at the 5' and 3' ends of the introns and cut the pre-mRNA at those points to remove the introns. Then, they bring the exons together and join them to generate the mature mRNA.