Final answer:
Eukaryotic mRNA contains non-coding regions known as introns, which are removed from the pre-mRNA during processing before translation, leaving only the coding exons.
Step-by-step explanation:
Eukaryotic mRNA contains non-coding regions called introns. These regions are transcribed along with the coding regions, known as exons, but are removed during the RNA splicing process before translation into proteins. Introns serve various roles, including gene regulation and mRNA transport, but they do not encode for functional proteins. Once introns are removed, the exons are spliced together to form mature mRNA, which then exits the nucleus and is translated into proteins by the ribosome. In eukaryotic organisms, the precise removal of introns is critical because even a single nucleotide error can lead to a nonfunctional protein due to a shift in the exon sequence.