BRAINCAKECell Wall Agents
Bacterial cells are surrounded by a cell wall made of peptidoglycan (murein): long polysaccharide chains held together by short peptide cross-links. The wall is strong and stops the cell bursting when water enters by osmosis. Human cells have no cell wall, so antibiotics that attack it have high selective toxicity.
Penicillin and related β-lactam antibiotics (such as amoxicillin and methicillin) inhibit the transpeptidase enzymes that form the cross-links between peptidoglycan chains. The antibiotic binds to the active site of the enzyme, so new cross-links cannot be made.
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Key terms in this lesson
- water potential
- A measure of the tendency of water molecules to move out of a solution, which determines the direction of osmosis.
More in Bacteria and Disease
- Antibiotics
- Broad-spectrum, Narrow spectrum, Bacteriostatic and Bactericidal
- Antimetabolites
- Protein synthesis Inhibitors
- Cell Membrane Agents
- DNA Gyrase Inhibitors
- Antibiotic Resistance
- Creating Drug-Resistant Bacteria
All 30 lessons in Bacteria and Disease · All Edexcel A-level Biology topics