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- any non-intron section of the coding sequence of a gene; together, the exons constitute the mRNA and are translated into protein
Source: Jenkins, John B. 1990. Human Genetics, 2nd Edition. New York: Harper & Row
- A DNA sequence that is ultimately translated into protein.
- An exon is the portion of a gene that codes for amino acids. In the cells of plants and animals, most gene sequences are broken up by one or more DNA sequences called introns. The parts of the gene sequence that are expressed 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--or interfere with--the exons.