Final answer:
Introns are sequences found within eukaryotic genes that do not code for functional proteins. They are removed through a process called splicing before protein synthesis. This ensures that the exons, which are the coding sequences, are joined together correctly.
Step-by-step explanation:
Eukaryotic genes are composed of coding sequences called exons and intervening sequences called introns. Introns are removed from the pre-mRNA during processing. Intron sequences in mRNA do not encode functional proteins. It is essential that all of a pre-mRNA's introns be completely and precisely removed before protein synthesis so that the exons join together to code for the correct amino acids. The process of removing introns and reconnecting exons is called splicing.