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.

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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.

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exon ¹ British  

/ ˈɛksɒn /

noun

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

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exon ² British  

/ ˈɛksɒn /

noun

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

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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

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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.)

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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 second exon encodes the same sequence, which is known as the classical tripeptide Cysteine-X-Cysteine, for both genes.

From Science Daily • Jan. 30, 2024

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

Known as exon skipping, this resulted in the downstream mRNA no longer being unreadable and in functional dystrophin being formed.

From Nature • Oct. 15, 2019

And in the exon portion of those sequences, I inserted a particular viral payload.

From Slate • Jul. 27, 2019

He soon returned, accompanied by an exon of the short robe, named Larchier.

From A Popular History of France from the Earliest Times, Volume 6 by Black, Robert