exon

¹ American  

[ek-son] / ˈɛk sɒn /

noun

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

---

exon ² American  

[ek-son] / ˈɛk sɒn /

noun

Genetics.

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

---

exon ¹ British  

/ ˈɛksɒn /

noun

1. one of the four officers who command the Yeomen of the Guard

---

exon ² British  

/ ˈɛksɒn /

noun

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

---

exon Scientific  

/ ĕk′sŏn /

1. 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.

2. Compare intron

---

exon Cultural  

1. 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.)

---

Other Word Forms

• exonic adjective

Etymology

Origin of exon¹

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

Origin of exon²

1975–80; ex(pressed sequence) + -on ¹

Example Sentences

The active splicing factor splices out the inhibitory exon in the transcription factor, which turns on the genes that produce collagen.

From Science Daily • Apr. 26, 2024

The intron is transcribed into mRNA, but this noncoding mRNA is edited out before translation of the coding portion, or exon, of a gene.

From Textbooks • Jun. 9, 2022

Krainer realized that there were similarities between the defects associated with SMA and one of the mechanisms he had been studying—namely, a mistake that occurs when an important exon is inadvertently lost during RNA splicing.

From Scientific American • Oct. 20, 2021

Importantly, even if an exon is missing, functional dystrophin can still be made.

From Nature • Oct. 15, 2019

I do not believe that there could be found under heaven another man like this exon.

From A Popular History of France from the Earliest Times, Volume 5 by Black, Robert