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How do archaeal cell walls differ from bacterial cell walls?
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Microbiology
Photomicrograph of Streptococcus pyogenes, a bacterium that can cause scarlet fever. (Magnified about 900Γ.)
The primary difference between bacterial and archaeal cell walls lies in their chemical composition. Bacterial cell walls are characterized by the presence of peptidoglycan, a rigid polymer consisting of repeating sugar chains (N-acetylglucosamine and N-acetylmuramic acid) cross-linked by peptide bridges.1
In contrast, Archaea do not contain peptidoglycan. Their cell wall structures vary significantly:1
- Alternative Polymers: Some archaea possess a wall material similar to peptidoglycan, but they utilize talosaminuronic acid instead of muramic acid.1
- Protein-based Walls: Many other archaeal species utilize proteins as the primary constituent of their cell walls.1
- Lack of Rigid Walls: Certain archaeal species lack a rigid cell wall entirely.1
Additionally, while bacterial membranes are composed of lipids linked to glycerol by ester bonds, archaeal membrane lipids are distinct, consisting of branched isoprenoids linked to glycerol by ether bonds.1