Which of the following is a characteristic shared by both the domains Bacteria and Archaea?

• A. They lack a membrane-bound nucleus.
• B. They are exclusively found in extreme environments.
• C. They possess peptidoglycan in their cell walls.
• D. They use eukaryotic-type ribosomes for protein synthesis.

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the question is asking for a characteristic that is common to both Bacteria and Archaea domains.
2. Step 2: Recall that both Bacteria and Archaea are prokaryotes, meaning they do not have a membrane-bound nucleus. This is a fundamental trait distinguishing prokaryotes from eukaryotes.
3. Step 3: Evaluate the other options: 'exclusively found in extreme environments' applies mainly to some Archaea but not all Bacteria; 'possess peptidoglycan in their cell walls' is true for Bacteria but not Archaea; 'use eukaryotic-type ribosomes' is incorrect because both have prokaryotic-type ribosomes, though Archaea's ribosomes are somewhat different.
4. Step 4: Conclude that the shared characteristic is the lack of a membrane-bound nucleus, which is a defining feature of prokaryotic cells including both Bacteria and Archaea.
5. Step 5: Summarize that this characteristic reflects their cellular organization and is key to differentiating them from eukaryotic organisms.