Question

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Penicillin is an antibiotic that is used for killing bacteria. Reason (R): Antibiotic penicillin kills bacteria by inhibiting bacterial cell wall synthesis. In the light of the above statements, choose the most appropriate answer from the options given below:

• A. Both (A) and (R) are correct and (R) is the correct explanation of (A) \
• B. Both (A) and (R) are correct but (R) is not the correct explanation of (A) \
• C. (A) is correct but (R) is not correct \
• D. (A) is not correct but (R) is correct

Hint:

Penicillin destroys the cellular "brick mortar" (peptidoglycan cross-links). Without a strong wall, water rushes into the bacterium and causes it to pop.

Answer 1

The Correct Option is A

Step 1: Concept $\beta$-lactam antibiotics target specific structural components unique to bacterial anatomy to kill bacterial cells without harming eukaryotic host structures.

Step 2: Meaning Inhibiting synthesis means stopping the cross-linking of the protective peptidoglycan layer, leaving the bacterial cell vulnerable to osmotic pressure.

Step 3: Analysis * Assertion (A) is correct: Penicillin is a classic, widely used bactericidal antibiotic prescribed to treat a variety of susceptible bacterial infections. * Reason (R) is correct: Mechanistically, the $\beta$-lactam ring of penicillin binds to and inhibits transpeptidase enzymes (penicillin-binding proteins). This stops the cross-linking of peptidoglycan chains, weakening the cell wall until the bacterium bursts from osmotic lysis. * Explanation assessment: The reason details the exact biochemical mechanism behind the therapeutic effect mentioned in the assertion, providing a direct explanation.

Step 4: Conclusion Both statements are true, and (R) provides the logical mechanism that explains (A). Final Answer: (A)