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Questions and Answers
What is a unique feature of almost all prokaryotic cells related to their cell structure?
Which component is involved in the cross-linking of peptidoglycan in bacterial cell walls?
What distinguishes the peptidoglycan structure of S. aureus from that of E. coli?
Which amino acid is uniformly present in Gram-negative peptidoglycans for cross-linking?
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The glycan backbone of peptidoglycans consists of repeating groups of which disaccharide?
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Study Notes
Prokaryotic Cell Walls
- Peptidoglycan is a defining feature of most prokaryotic cell walls, with exceptions being Halobacterium halobium and mycoplasmas.
- Peptidoglycan biosynthesis enzymes serve as targets for antibiotics, inhibiting peptidoglycan synthesis.
- Peptidoglycan consists of a repeating disaccharide backbone of N-acetylmuramic acid (MurNAc) and N-acetylglucosamine (GlcNAc) linked by β1,4 glycosidic bonds.
- Tetrapeptides are attached to MurNAc residues, consisting of L-alanine-D-isoglutamic acid-L-lysine (or diaminopimelic acid)-D-alanine.
- Cross-linking occurs between tetrapeptides, either directly or via a peptide bridge.
- In Staphylococcus aureus, a glycine pentapeptide bridge links adjacent peptide structures, resulting in high cross-linking.
- Escherichia coli has a less cross-linked peptidoglycan structure, leading to a more open mesh.
- Diaminopimelic acid or lysine serves as the ε-amino group for cross-linking, consistently found in Gram-negative bacteria.
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Description
Explore the essential features of prokaryotic cell walls, focusing on peptidoglycan composition and biosynthesis. Discover how this unique polymer influences antibiotic action and cell structure variability among different bacterial species. This quiz delves into the biochemical intricacies of cell wall architecture.
