exon¹

[ek-son] /ˈɛk sɒn/

noun

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

Also called exempt.

Origin

1645-55; earlier exant, for French exempt (spelling altered to show French pronunciation)

exon²

[ek-son] /ˈɛk sɒn/

noun, Genetics.

any portion of an interrupted gene that is represented in the RNA product and is translated into protein.

Compare intron.

Origin

1975-80; ex(pressed sequence) + -on¹

British Dictionary definitions for exon

exon¹

/ˈɛksɒn/

noun

(Brit) one of the four officers who command the Yeomen of the Guard

Word Origin

C17: a pronunciation spelling of French exemptexempt

exon²

/ˈɛksɒn/

noun

any segment of a discontinuous gene the segments of which are separated by introns Compare intron

Derived Forms

exonic, adjective

Word Origin

C20: from ex-1 + -on

exon in Medicine

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.

ex·on'ic adj.

exon in Science

exon

(ěk'sŏn)
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.

exon in Culture

exon definition

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.)