The codon is on the mRNA, the anticodon on the tRNA
- The idea
- Predict
- See it
- Why
- Check
The idea
“The three bases on the tRNA are the codon, so I can look them up in the codon table.”
Both are three bases, and they sit side by side in the ribosome. Under time pressure, the two names swap easily.
The short version
The mistake: The three bases on the tRNA are the codon, so I can look them up in the codon table.
What's actually true: The codon is on the mRNA and is what the codon table lists, and the anticodon on the tRNA is its complement.
- A codon is three bases on the mRNA. Codon tables list codons, read 5' to 3'.
- An anticodon is three bases on a tRNA. It pairs with the codon, A with U and G with C, running the opposite direction.
- The other end of the tRNA holds the amino acid for that codon. An enzyme called aminoacyl-tRNA synthetase attaches it.
On the exam: Codon tables list mRNA codons. For an anticodon written 5' to 3', pair each base, then reverse the order.