- (in Britain) one of four yeomen of the guard who act as commanding officers in the absence of higher authority.
Origin of exon1
1645–55; earlier exant, for French exempt (spelling altered to show French pronunciation)
Also called exempt.
- any portion of an interrupted gene that is represented in the RNA product and is translated into protein.
Origin of exon2
1975–80; ex(pressed sequence) + -on1
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for exon
We have not seen dominicum used as a substantive; but in the Exon.Domesday Book and Beyond
Frederic William Maitland
I do not believe that there could be found under heaven another man like this exon.
He soon returned, accompanied by an exon of the short robe, named Larchier.
The exon looked all round the room; he knew every one of the magistrates; the accused were sitting right in front of him.
Exon, eks′on, n. one of the four officers of the yeomen of the Royal Guard.
- British one of the four officers who command the Yeomen of the Guard
C17: a pronunciation spelling of French exempt exempt
- any segment of a discontinuous gene the segments of which are separated by intronsCompare intron
C20: from ex- 1 + -on
- A nucleotide sequence in DNA that carries the code for the final mRNA molecule and thus defines a protein's amino acid sequence.coding sequence
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
- 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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.