Which statement best describes a key difference between Bacteria and Archaea?

• A. Bacteria lack cell membranes, whereas Archaea have cell membranes.
• B. Archaea have membrane lipids with ether-linked branched isoprenoids, whereas Bacteria typically have ester-linked fatty acids.
• C. Archaea lack ribosomes, whereas Bacteria have 70S ribosomes.
• D. Archaea have peptidoglycan cell walls, whereas Bacteria do not.

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the basic cellular structures common to both Bacteria and Archaea, such as the presence of cell membranes and ribosomes, to identify which features are shared and which differ.
2. Step 2: Recall that both Bacteria and Archaea have cell membranes, but the chemical composition of their membrane lipids differs significantly. Focus on the type of lipid linkages and the structure of the lipid chains.
3. Step 3: Recognize that Bacteria typically have membrane lipids with ester-linked fatty acids, while Archaea have membrane lipids with ether-linked branched isoprenoids. This difference affects membrane stability and function.
4. Step 4: Note that both Bacteria and Archaea have ribosomes, generally of the 70S type, so the statement about Archaea lacking ribosomes is incorrect.
5. Step 5: Understand that peptidoglycan is a component of bacterial cell walls but is absent in Archaea, which have different cell wall compositions such as pseudopeptidoglycan or other polymers.