Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
The outer membrane is a lipid bilayer found in Gram-negative bacteria, serving as an additional protective barrier. It contains lipopolysaccharides that contribute to the structural integrity and defense against harmful substances.
5 Must Know Facts For Your Next Test
The outer membrane is unique to Gram-negative bacteria.
It contains porins, which are proteins that allow the passage of certain molecules.
Lipopolysaccharides (LPS) in the outer membrane can trigger strong immune responses in hosts.
The space between the outer membrane and the plasma membrane is called the periplasmic space.
Antibiotics like polymyxins target and disrupt the outer membrane.
Review Questions
Related terms
Gram-negative bacteria: Bacteria characterized by a thin peptidoglycan layer and an outer membrane.
Lipopolysaccharide (LPS): A molecule consisting of lipids and polysaccharides found in the outer membrane of Gram-negative bacteria.
Porins: Proteins located in the outer membrane that permit the diffusion of small molecules.