What substance provides rigidity to bacterial cell walls? Give its structure.
The peptidoglycan which is a macromolecular network and consists of repeating disaccharides attached to polypeptides provides rigidity to the bacterial cell walls. The disaccharide comprises two monosaccharides N-acetyl glucosamine (NAG) and N-acetyl muramic acid (NAM). The linkage between the two monosaccharides is known as, β -1, 4 linkage. The tetrapeptide side chains form the polypeptide links. The parallel tetrapeptide side chains are linked by peptide cross bridge.