What is the major structural component of the cell wall in most bacteria?

• A. Peptidoglycan
• B. Cellulose
• C. Chitin
• D. Lignin

Answer: (A)

The major structural component of most bacterial cell walls is peptidoglycan. It forms a strong, mesh-like layer outside the cell membrane, built from long chains of sugars (repeating units of N-acetylglucosamine and N-acetylmuramic acid) that are cross-linked by short peptide bridges. This cross-linking creates rigidity that helps bacteria withstand the turgor pressure of their environment and maintain shape.

Other polymers mentioned belong to different organisms: cellulose is the main component of plant cell walls; chitin is found in fungal cell walls and some invertebrates; lignin is a plant polymer that adds rigidity in wood. It’s also worth noting that a few bacteria (like Mycoplasma) lack a cell wall entirely, but in the majority the peptidoglycan layer is the key structural feature. Because peptidoglycan is essential to bacterial integrity, many antibiotics target its synthesis, weakening the wall and causing the cell to lyse.