Question

Which one of the following characteristics is ABSENT in Archaea?

• A. Pseudomurein
• B. Paracrystalline surface layer (S-layer)
• C. Peptidoglycan
• D. Circular chromosome

Hint:

Archaea differ from bacteria mainly because they lack true peptidoglycan in their cell walls and possess unique membrane lipids.

Answer 1

The Correct Option is C

Step 1: Understand Archaea.
Archaea are prokaryotic microorganisms that are distinct from bacteria and eukaryotes in terms of cell wall composition, membrane lipids, and genetic machinery.

Step 2: Analyze pseudomurein.
Some archaeal species possess pseudomurein in their cell walls. Pseudomurein resembles peptidoglycan structurally but differs chemically. Therefore, option (A) is present in Archaea.

Step 3: Analyze S-layer.
Many Archaea possess a paracrystalline surface layer called the S-layer, which provides protection and structural support. Hence, option (B) is also present in Archaea.

Step 4: Analyze circular chromosome.
Like bacteria, Archaea generally possess circular chromosomes as their genetic material. Therefore, option (D) is a characteristic of Archaea.

Step 5: Analyze peptidoglycan.
True peptidoglycan is a characteristic component of bacterial cell walls and is absent in Archaea. Archaeal cell walls contain pseudomurein or other polymers instead.

Step 6: Compare all the options.
Among the given options, peptidoglycan is the only feature absent in Archaea.

Step 7: Final conclusion.
Therefore, the characteristic absent in Archaea is peptidoglycan.
\[ \boxed{\text{Peptidoglycan}} \]
Hence, the correct answer is option (C).