peptidoglycan

biology

Also known as: murein

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July 1, 2026

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Peptidoglycan is a crucial component found in the cell walls of bacteria, providing structural rigidity and determining the cell's shape. It is a large polymer composed of repeating sugar units, specifically N-acetylglucosamine and N-acetylmuramic acid, which are cross-linked by peptide bridges.1

This unique structure is essential for bacterial survival and is a target for many antibiotics, such as penicillin, which disrupt the formation of these peptide bridges. The presence and thickness of the peptidoglycan layer also differentiate bacteria, notably in the Gram stain test, where it influences how cells retain a blue dye. Peptidoglycan is not found in archaea or eukaryotic cells.1

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bacteria
The cell envelope
…of a huge molecule called peptidoglycan (or murein). In gram-positive bacteria the peptidoglycan forms a thick meshlike layer that retains the blue dye of the Gram stain by trapping it in the cell. In contrast, in gram-negative bacteria the peptidoglycan layer is very thin (only one or two molecules deep),…
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…of a huge molecule called peptidoglycan (or murein). In gram-positive bacteria the peptidoglycan forms a thick meshlike layer that retains the blue dye of the Gram stain by trapping it in the cell. In contrast, in gram-negative bacteria the peptidoglycan layer is very thin (only one or two molecules deep),…
Read More