This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of nucleic acids, Subject name: Biochemistry
Inhibition of protein synthesis in translocation steps occurs by 
Select and explain. 
A. Tetracycline, B. Erythromycin, C. Aminoglycosides, D. Penicillin
B: Erythromycin
Answer: B: Erythromycin 
Explanation: Reversible Inhibitors in bacteria : These antibiotics are bacteriostatic . Tetracycline bind to the 30S subunit of bacterial ribosome and so inhibit attachment of aminoacyl tRNA to the A site of ribosomes. Chloramphenicol inhibits the peptidyl transeferase acitivity of bacterial ribosomes. Erythromycin (macrolides) and clindamycin prevent the translocation process. REFERENCE : DM.VASUDEVAN.TEXTBOOK ; SEVENTH EDITION ; PAGE NO : 605.