The cell wall of bacteria

• Protect cells from mechanical injury and osmotic pressure.
• Is 3-25 nm thick.
• Composed of peptidoglycan, a complex of oligosaccharides and proteins.
• Oligosaccharides consist of a long chain of alternating N-acetyl glucosamine (Glc NAC) and N-acetyl muramic acid (NAM) linked by β ( 1–>4) bond.
• A circular segment of DNA in the cytoplasm is called a plasmid.
• The cell wall of the gram-negative bacteria Staphylococcus aureus is made up of N-acetyl glucosamine covalently bonded with N-acetyl muramic acid by β ( 1à 4)-O- glycosidic bond.
• The cell wall of gram-negative bacteria is absent of pentaglycine and teichoic acid.