Question

Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: Archaea are insensitive to chloramphenicol antibiotic
Reason R: Archaea do not contain peptidoglycan in the cell wall
In light of the above statements, choose the correct answer from the options given below:

• A. Both A and R are true and R is the correct explanation of A
• B. Both A and R are true but R is NOT the correct explanation of A
• C. A is true but R is false
• D. A is false but R is true

Hint:

Always identify the target of the antibiotic mentioned. Chloramphenicol targets ribosomes, while beta-lactams target the cell wall. This prevents making false logical connections between cellular structures and drug resistance.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
The domain Archaea represents an evolutionary lineage distinct from Bacteria and Eukarya.
They possess unique structural, chemical, and genetic characteristics that render them insensitive to many antibiotics designed to target true bacteria.

Step 2: Detailed Explanation:
Assertion A Analysis: Chloramphenicol is an antibiotic that inhibits bacterial protein synthesis by binding to the peptidyl transferase center of the 50S ribosomal subunit.
Archaea possess a translation system that shares structural similarities with eukaryotes.
Their ribosomes and translation factors differ in sequence and structure from their bacterial counterparts, making archaeal protein synthesis insensitive to chloramphenicol.
Thus, Assertion A is correct.
Reason R Analysis: Unlike bacteria, whose cell walls are composed of peptidoglycan (murein), Archaea lack peptidoglycan entirely.
Their cell walls consist of alternative polymers such as pseudomurein, complex polysaccharides, glycoproteins, or protein S-layers.
Thus, Reason R is also correct.
Evaluating the Relationship: Although both statements are correct, Reason R does not explain Assertion A.
Chloramphenicol targets protein translation (the ribosome), not the cell wall or peptidoglycan synthesis.
An antibiotic that targets the cell wall (such as penicillin) would have its insensitivity explained by the lack of peptidoglycan.
Therefore, R is not the correct explanation of A.

Step 3: Final Answer:
Hence, both A and R are true but R is NOT the correct explanation of A.