All of the Following are True About Prokaryotic Outer Membranes

Question

All of the following are true about prokaryotic outer membranes EXCEPT that they
A) are lipid bilayers composed of identical phospholipids.
B) are found only in Gram-negative bacteria.
C) contain endotoxin.
D) contain proteins involved in transport.
E) contain lipopolysaccharide.

Accepted Answer

Prokaryotic outer membranes are composed of an asymmetric lipid bilayer containing unique lipids such as lipopolysaccharide (LPS) and phospholipids with long-chain fatty acids in the outer leaflet and shorter-chain fatty acids in the inner leaflet. This gives rise to a distinct outer membrane structure that is different from the lipid bilayers in eukaryotes and archaea. The outer membrane of Gram-negative bacteria also contains porins, lipoproteins, and transport proteins embedded in the lipid bilayer, as well as endotoxin (LPS) in the outer leaflet. Prokaryotic outer membranes are only found in Gram-negative bacteria, while Gram-positive bacteria lack this structure.