Answer: Exons
Explanation:
In eukaryotic cell the primary transcript are very long the contains coding region (exons) and non coding region (introns)
The parts of the gene sequence that are expressed (coding region) in the protein are called exons, because they are expressed, while the parts of the gene sequence that are not expressed in the protein are called introns, because they come in between the exons.
Intron is a portion of a gene that does not code for amino acids. These Intron sequence are cleaved out and exons are spliced (I. E combine together) to form the mature mRNA molecule.
Exons are the mRNA parts that are kept and used to make protein.
