Bacterial cell wall

A structural layer outside the bacterial cell membrane that helps maintain cell shape and prevents osmotic pressure from rupturing the cell. Most bacterial cell walls contain peptidoglycan.

Peptidoglycan: A mesh-like polymer of sugars and short peptides that forms the main structural material in most bacterial cell walls. Its cross-linked mesh bears the mechanical load that keeps many bacterial cells intact.
Penicillin-binding proteins: A group of bacterial enzymes that build and remodel peptidoglycan, including enzymes that form peptide cross-links. They construct the wall’s cross-links and are targets of several beta-lactam antibiotics.
Gram-positive bacteria: Bacteria whose cell envelopes have a thick peptidoglycan layer and retain crystal violet during Gram staining. Their thick wall is exposed outside the membrane and contains teichoic acids.
Beta-lactam antibiotics: Antibiotics, including penicillins and cephalosporins, that inhibit bacterial cell-wall synthesis by targeting penicillin-binding proteins. They weaken peptidoglycan construction, especially in actively growing bacteria.
N-acetylglucosamine: A modified sugar that forms alternating units with N-acetylmuramic acid in peptidoglycan chains. It supplies one of the repeating sugar units in the wall’s glycan backbone.
Peptidoglycan transglycosylation: The enzymatic polymerization of peptidoglycan sugar units into glycan strands. This reaction extends the carbohydrate backbone as new wall material is inserted.
Gram-negative bacteria: Bacteria with a thin peptidoglycan layer between an inner membrane and an outer membrane. Their wall occupies the periplasm, beneath an additional outer membrane.
Vancomycin: A glycopeptide antibiotic that binds peptidoglycan precursors and inhibits bacterial cell-wall synthesis. It blocks wall assembly through a mechanism distinct from beta-lactam inhibition.
N-acetylmuramic acid: A sugar in bacterial peptidoglycan that carries the short peptide chains used for cross-linking. Its peptide attachments connect neighboring strands into a load-bearing network.
Autolysin: A bacterial enzyme that cleaves bonds in peptidoglycan. Controlled wall cutting permits growth and cell division; excessive cleavage can cause lysis.

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