The antibiotic erythromycin disrupts protein synthesis by preventing ribosomal translocation (movement of the ribosome relative to the mRNA). It does not affect any other step in protein synthesis. Suppose you are doing a translation reaction in vitro and you add erythromycin just before the 3rd peptide bond is about to be made. You wait a few minutes and look at the ribosome.

Circle the correct

a. The carboxyl end of AA #3 should now be covalently bonded directly to: (tRNA #2) (tRNA #3) (tRNA #4) (AA #2) (AA #3) (AA #4) (none of these).

b. Which tRNA will you find in the A site? (tRNA #1) (tRNA #2) (tRNA #3) (tRNA #4) (tRNA #5).

c. The tRNA in the A site will carry: (an amino acid) (a polypeptide) (neither) (either one)