exon
Low (specialist scientific/medical term)Specialist (genetics, molecular biology, biochemistry)
Definition
Meaning
A segment of a DNA or RNA molecule containing information coding for a protein or peptide sequence.
In genetics, the expressed region of a gene that remains in mature messenger RNA after splicing; the coding sequence. In law (historical), a sheriff's officer.
Linguistics
Semantic Notes
A 'gene' contains introns (non-coding sequences) and exons (coding sequences). Exons are spliced together after intron removal to form mature mRNA. The legal meaning is archaic and rarely encountered.
Dialectal Variation
British vs American Usage
Differences
No significant variation in meaning or usage. Pronunciation follows standard BrE/AmE patterns for similar words.
Connotations
Purely technical and neutral in both varieties.
Frequency
Used exclusively in scientific contexts in both regions; frequency is identical for specialists and zero for general public.
Vocabulary
Collocations
Grammar
Valency Patterns
exon of a geneexon in the sequenceexon encoding (a protein)exon involved inVocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Usage
Context Usage
Business
Not used.
Academic
Core term in genetics and molecular biology papers and textbooks.
Everyday
Virtually never used.
Technical
Fundamental unit describing gene architecture in research, diagnostics, and biotech.
Examples
By Part of Speech
adjective
British English
- The exon boundaries were clearly mapped.
- Exon duplication events are studied.
American English
- The exon boundaries were clearly mapped.
- Exon duplication events are studied.
Examples
By CEFR Level
- Genes have parts called exons and introns.
- Exons contain the code for proteins.
- The mutation was located in the third exon of the gene, altering the protein's function.
- During RNA splicing, introns are removed and exons are joined together.
- Alternative splicing allows a single gene to produce multiple proteins by combining different exons.
- The conservation of this exon across vertebrate species suggests a crucial functional role.
Learning
Memory Aids
Mnemonic
Think 'EXpressed regiON' → EXON. It's the part that EXits the nucleus to be expressed.
Conceptual Metaphor
A gene is like an instruction manual. The exons are the crucial paragraphs containing the actual steps, while the introns are the unnecessary filler notes that are removed before sending the instructions to the workshop (ribosome).
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Do not confuse with Russian 'экзон' – a direct transliteration. Ensure understanding of the 'coding vs. non-coding' conceptual pair (экзон/интрон).
Common Mistakes
- Pronouncing it as /ˈiːksɒn/ (like 'ex-own').
- Using it as a general term for any gene part.
- Confusing it with 'axon' (part of a neuron).
Practice
Quiz
What is the primary functional distinction between an exon and an intron?
FAQ
Frequently Asked Questions
No, it is a highly specialist term used almost exclusively in genetics, molecular biology, and related fields.
Yes, some genes, particularly in prokaryotes and some simple eukaryotes, are 'intronless' and consist of a single exon.
A specific mutation or therapeutic approach that causes an exon to be excluded from the final mRNA transcript during splicing, often altering the protein product.
No direct etymological connection. 'Exon' comes from 'expressed region', while 'exosome' refers to an extracellular vesicle or a protein complex for RNA degradation.