In marked contrast to prokaryotic genes where proteins are encoded by a continuous sequence of triplet codons and the vast popular of protein-coding genes in eukaryotes are discontinuous. The coding sections of the gene called as exons are interrupted by noncoding sections of DNA called as introns that is shown in the figure. Nevertheless the triplet codons within the exons and the order of exons themselves in the gene

                          Figure: Structure and expression of a protein coding gene in a eukaryote.