Question

Cell wall of archaebacteria do not contain

• A. Proteins
• B. Glycoproteins
• C. Polysaccharides
• D. Peptidoglycans

Hint:

Remember: Archaea = No Peptidoglycan.
Bacteria = Peptidoglycan present.
This is why Archaea are resistant to Penicillin.

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
The question focuses on the fundamental biochemical differences between the domains Archaea and Bacteria.
The cell wall is a primary diagnostic feature used to distinguish these microorganisms.
Archaebacteria are known for their ability to survive in extreme environments, which is facilitated by their unique cell wall and membrane structures.

Step 2: Detailed Explanation:

• Characteristics of Archaebacterial Cell Walls: Unlike Eubacteria (true bacteria), the members of the domain Archaea do not possess peptidoglycan (murein) in their cell walls.
Peptidoglycan is a polymer of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) cross-linked by short peptides.

• Alternative Components: Archaebacteria have developed diverse cell wall compositions.
Many possess a surface layer (S-layer) made of proteins or glycoproteins.
Some contain complex polysaccharides like methanochondroitin.
Others have "Pseudomurein" (pseudopeptidoglycan), which contains N-acetyltalosaminuronic acid instead of NAM and L-amino acids instead of D-amino acids.

• Evolutionary Significance: The absence of peptidoglycan makes Archaebacteria naturally resistant to antibiotics that inhibit cell wall synthesis, such as Penicillin and Lysozyme, which specifically target the peptidoglycan structure.

• Option Analysis: Options (A), (B), and (C) represent components that can be present in various archaeal lineages.
Option (D), Peptidoglycan, is exclusively found in the domain Bacteria.

Step 3: Final Answer:
Therefore, the component that archaebacteria do not contain in their cell wall is Peptidoglycans.