 Type of RNA that functions as an interpreter in translation  Each tRNA molecule has a specific anticodon and a site of attachment for an amino acid  Each tRNA picks up a specific amino acid based on its anticodon

 Anticodon – specific sequence of 3 exposed nucleotides found in tRNA; complementary to codon of mRNA  2 important sites › Anticodon › Point of attachment to amino acid

 Type of RNA that, together with proteins, make up ribosomes; most abundant type of RNA  Ribosome composed of 2 subunits – small and large

 Eukarytoic ribosomes are larger and of different composition  Antibiotics can inactivate prokaryotic ribosomes (but not the eukaryotic ribosomes)  can be used to treat bacterial infections

 Initiation establishes exactly where translation will begin  2 steps › mRNA binds to small ribosomal subunit; initiator tRNA binds to the start codon (AUG) of mRNA; tRNA UAC carries Methionine › Large ribosomal subunit binds to the small one placing the initiator tRNA in the P site; A site is open for the next tRNA

 P site – the ribosomal binding site that holds the tRNA carrying the growing polypeptide (peptidyl tRNA)  A site – the ribosomal binding site that holds the incoming tRNA that holds the new amino acid  E site – the ribosomal release site for tRNA molecules that release the growing polypeptide

 Codon Recognition – incoming tRNA anticodon pairs with mRNA codon in the A site bringing in a new amino acid  Peptide Bond Formation – peptide bond forms between the amino acid in A site and the amino acid in the P site; the tRNA in the P site releases its amino acid once the bond is formed  Translocation – ribosome moves so that the A site tRNA is now in the P site; leaving the A site open for a new tRNA

 Termination – when the ribosome reaches a stop codon at the A site a release factor binds to the mRNA this triggers the release of the the polypeptide from the last tRNA; mRNA is released from the ribosome and the ribosome subunits separate