This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
All pencillins act by: September 2007 
Select and explain. 
A. Inhibiting protein synthesis, B. Inhibiting cell wall synthesis, C. Antifolate, D. Inhibitis DNA gyrase
B: Inhibiting cell wall synthesis
Answer: B: Inhibiting cell wall synthesis 
Explanation: Ans. B: Inhibiting cell wall synthesis All penicillin derivatives produce their bacteriocidal effects by inhibition of bacterial cell wall synthesis. Specifically, the cross linking of peptides on the mucosaccharide chains is prevented. If cell walls are improperly made cell walls allow water to flow into the cell causing it to burst and bacterial lysis occurs.