Overview Structure cloverleaf structure 3' aminoacyl end = CCA bound covalently to amino acid (AA) Charging purpose adds correct AA to correct tRNA each AA has a specific tRNA correct AA is only checked when attachment occurs by aminoacyl-tRNA synthetase to the tRNA thus, if a AA is mischarged, it has no other correction mechanism and will insert for the AA specified by the tRNA anticodon charged tRNA contains the needed energy for the formation of the peptide bond process tRNA + ATP + aa → aa-tRNA + AMP + PPi catalyzed by aminoacyl-tRNA synthetase inhibited by tetracyclines Wobble first 2 nucleotide positions provide specificity for an individual amino acid e.g., mRNA triplets CUU, CUC, CUA, CUG all code for Leu genetic code is degenerate all amino acids except for one have more than one codon explains silent mutations mutation from CUU to CUC would not alter the protein