ref Growi Protein Tunnel chain Growing poly peptide 50s Chloramphenicol Binds to 50s portion and inhibits formation of peptide bond 30s 50s rtion mRNA (a) Three-dimensional detail of the protein Protein sythesis site synthesis site showing the 30S and 50S subunit portions of the 70S prokaryotic Erythromycin tRNA Binds to 50S portion, prevents translocation-movement of ribosome along mRNA RNA 30S portion 70s prokaryotic ribosome Tetracyclines Translation Interfere with attachment of Streptomycin tRNA to mRNA-ribosome complex Changes shape of 30S portion causes code on mRNA to be read incorrectly Direction of ribosome (b) In the diagram the black arrows indicate the different points at which chloramphenicol, erythromycin, the tetracyclines, and streptomycin exert their activities yright e2004 Pearson Education, Ine publishing as Ben amin Cummings.ref 23