Dictionary > Codon

Codon


Reviewed by: Mary Anne Clark, PhD


Definition
noun
A‌ ‌codon‌ ‌is‌ ‌the‌ ‌amino‌ ‌acid‌ ‌coding‌ ‌unit‌ ‌in‌ ‌DNA‌ ‌or‌ ‌messenger‌ ‌RNA.‌ ‌Each‌ ‌codon‌ ‌corresponds‌ ‌
to‌ ‌a‌ ‌specific‌ ‌amino‌ ‌acid,‌ ‌and‌ ‌the‌ ‌string‌ ‌of‌ ‌codons‌ ‌in‌ ‌mRNA‌ ‌specifies‌ ‌the‌ ‌order‌ ‌of‌ ‌amino‌ ‌
acids‌ ‌in‌ ‌the‌ ‌encoded‌ ‌protein.‌ ‌Each‌ ‌codon‌ ‌consists‌ ‌of‌ ‌a‌ ‌set‌ ‌of‌ ‌three‌ ‌adjacent‌ ‌‌nucleotide‌s,‌ ‌
also‌ ‌called‌ ‌‌triplet‌s,‌ ‌in‌ ‌‌mRNA‌‌ ‌that‌ ‌base-pair‌ ‌with‌ ‌the‌ ‌three‌ ‌bases‌ ‌of‌ ‌the‌ ‌corresponding‌ ‌
anticodon‌‌ ‌of‌ ‌a‌ ‌‌tRNA‌‌ ‌‌molecule‌‌ ‌that‌ ‌carries‌ ‌a‌ ‌particular‌ ‌‌amino‌ ‌acid‌.‌ ‌The‌ ‌ribosome,‌ ‌where‌ ‌
protein‌ ‌synthesis‌ ‌occurs,‌ ‌has‌ ‌binding‌ ‌sites‌ ‌where‌ ‌the‌ ‌tRNAs‌ ‌can‌ ‌match‌ ‌up‌ ‌with‌ ‌their‌ ‌
corresponding‌ ‌codons‌ ‌in‌ ‌the‌ ‌mRNA.‌

Supplement
For example:
GCC (GuanineCytosine-Cytosine) → alanine
GUU (Guanine-Uracil-Uracil) → valine
CUA (Cytosine-Uracil-Adenine) → leucine
UCA (Uracil-Cytosine-Adenine) → serine

Related terms: genetic code, ambiguous codon, start codon, stop codon.
Synonym: coding triplet.

Compare: anticodon.

See also: pyrimidine, purine.


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