Question

Penicillin acts by inhibiting _______

• A. Protein synthesis
• B. Cell wall synthesis
• C. DNA replication
• D. Folic acid synthesis

Hint:

Penicillin and cephalosporins are \(\beta\)-lactam antibiotics that inhibit bacterial cell wall synthesis.

Answer 1

The Correct Option is B

The given question asks about the mechanism by which Penicillin acts. Let's explore the options and find the correct answer.

1. Protein synthesis: Protein synthesis is the process by which cells generate new proteins, mediated by ribosomes translating RNA into polypeptide chains. Antibiotics like tetracyclines and macrolides inhibit protein synthesis, but Penicillin does not. Therefore, this option is incorrect.
2. Cell wall synthesis: Penicillin is classified as a β-lactam antibiotic. It works by inhibiting the transpeptidase enzyme, which is crucial for the cross-linking of peptidoglycan layers in bacterial cell walls. This inhibition weakens the cell wall and causes the bacteria to lyse due to osmotic pressure. Therefore, this is the correct mechanism of action for Penicillin.
3. DNA replication: DNA replication involves the duplication of a cell's DNA before cell division. Antibiotics like fluoroquinolones target DNA replication. Penicillin does not affect DNA replication, making this option incorrect.
4. Folic acid synthesis: Inhibitors of folic acid synthesis, such as sulfonamides and trimethoprim, prevent bacteria from synthesizing folate, which is necessary for DNA and RNA synthesis. Penicillin does not inhibit this pathway, so this option is incorrect.

Based on the explanations above, the correct answer is that Penicillin acts by inhibiting cell wall synthesis.