| 1. | to free from an obligation or liability to which others are subject; release: to exempt a student from an examination. |
| 2. | released from, or not subject to, an obligation, liability, etc.: organizations exempt from taxes. |
| 3. | a person who is exempt from an obligation, duty, etc. |
| 4. | (in Britain) exon. |

| (in Britain) one of four yeomen of the guard who act as commanding officers in the absence of higher authority. |

Stretches of DNA in genes that code for proteins. In eukaryotes, exons in a given gene are generally separated from each other by stretches of DNA that do not contain instructions for constructing proteins. (Compare intron.)
exon ex·on (ěk'sŏn)
n.
A nucleotide sequence in DNA that carries the code for the final mRNA molecule and thus defines a protein's amino acid sequence. Also called coding sequence.
| exon (ěk'sŏn) Pronunciation Key
A segment of a gene that contains information used in coding for protein synthesis. Genetic information within genes is discontinuous, split among the exons that encode for messenger RNA and absent from the DNA sequences in between, which are called introns. Genetic splicing, catalyzed by enzymes, results in the final version of messenger RNA, which contains only genetic information from the exons. Compare intron. |