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 exon¹

1975–80; ex(pressed sequence) + -on ¹

Example Sentences

Cummings and colleagues demonstrated that, when an individual carries a pLoF variant in an ‘intolerant’ gene, the variant is often in an exon that shows this restricted expression, thus limiting its effect.

From Nature

The SMN2 gene had a variation that rendered it inactive by causing a particular coding chunk, exon 7, to be ignored.

From Scientific American

The latter is an example of an ‘exon’ skipping drug, which uses an ASO to block only the mutated portion of a gene from being expressed.

From Nature

The investigators are testing a strategy called exon skipping: putting a molecular bandage over a tiny mutation in a large gene.

From New York Times

RNA molecules that are newly transcribed from DNA contain intron and exon sequences.

From Nature