Which of the following correctly describes a key difference between bacterial and archaeal cell membranes?

• A. Bacterial membranes are typically monolayers, while archaeal membranes are always bilayers.
• B. Bacterial membranes contain ester-linked phospholipids, while archaeal membranes contain ether-linked phospholipids.
• C. Archaeal membranes are composed of phospholipids with fatty acid tails, while bacterial membranes have isoprenoid tails.
• D. Both bacterial and archaeal membranes contain peptidoglycan as a major component.

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the composition of bacterial cell membranes. Bacterial membranes typically consist of a phospholipid bilayer where the phospholipids have fatty acid tails linked to glycerol by ester bonds.
2. Step 2: Understand the composition of archaeal cell membranes. Archaeal membranes also have phospholipids, but these are linked to glycerol by ether bonds instead of ester bonds, and their lipid tails are made of isoprenoid chains rather than fatty acids.
3. Step 3: Recognize the structural difference in the lipid linkages: ester linkages in bacteria versus ether linkages in archaea. This difference affects membrane stability and function, especially in extreme environments where archaea often thrive.
4. Step 4: Note that bacterial membranes are generally bilayers, while archaeal membranes can be bilayers or monolayers depending on the species, but the key difference lies in the chemical nature of the lipid linkages, not the membrane layering.
5. Step 5: Understand that peptidoglycan is a component of bacterial cell walls, not membranes, and it is absent in archaeal membranes, which have different cell wall compositions. This helps eliminate incorrect options related to peptidoglycan.