Codon vs Anticodon
A codon is a three-base sequence on mRNA. An anticodon is the complementary three-base sequence on tRNA that pairs with the codon during translation.
Use this page to convert a codon into its matching anticodon, then review how mRNA, tRNA, direction, and stop codons are handled.
Codon to anticodon lookup
Enter one RNA or DNA codon to see its mRNA codon, DNA coding triplet, tRNA anticodon, and amino acid.
mRNA codon
5'-AUG-3'
tRNA anticodon
3'-UAC-5'
DNA coding triplet
5'-ATG-3'
Amino acid
Methionine
Anticodons are shown in the complementary 3' to 5' orientation. Stop codons are recognized by release factors, not standard aminoacyl-tRNAs.
Common examples
| mRNA codon | tRNA anticodon | Amino acid | |
|---|---|---|---|
| 5'-AUG-3' | 3'-UAC-5' | Methionine | Open codon page |
| 5'-UUU-3' | 3'-AAA-5' | Phenylalanine | Open codon page |
| 5'-GCU-3' | 3'-CGA-5' | Alanine | Open codon page |
| 5'-UGG-3' | 3'-ACC-5' | Tryptophan | Open codon page |
| 5'-UAA-3' | No standard tRNA anticodon | Methionine | Open codon page |
What is the difference?
Codons are read on mRNA in the 5' to 3' direction. A tRNA anticodon pairs with the codon in the opposite, antiparallel direction. For example, mRNA 5'-AUG-3' pairs with tRNA 3'-UAC-5'.
Why direction matters
Some diagrams write only the matching bases, while others include 5' and 3' labels. The labels matter: reversing the sequence changes the way it is written.
What about stop codons?
Standard stop codons are recognized by release factors, not by a standard aminoacyl-tRNA carrying an amino acid.