Translation

initiation

• mRNA binds w. small ribosomal unit (AUG = starting codon)

• tRNA carrying a.a. methionine binds to start codon

• large ribosomal unit joins with tRNA-MET at P site

elongation

• new tRNA holding next a.a attaches to A site of large ribosomal subunit

• tRNA at P site holds growing chain, peptide bonds are formed (covalent)

• as ribosome moves along mRNA (5’-3’), tRNA in P site moves to E site

  • passes the the growing peptide to next tRNA

  • empty tRNA leaves/exits E site

• *TRNA CAN BE REUSED WITH NEW AAs UNTIL STOP CODON

termination

• begins when stop codon reached

  • UAA/UGA/UAG

• polypeptide released from P site and ribosome/mRNA complex detaches