<P> Peptidoglycan , also known as murein , is a polymer consisting of sugars and amino acids that forms a mesh - like layer outside the plasma membrane of most bacteria , forming the cell wall . The sugar component consists of alternating residues of β - ( 1 , 4 ) linked N - acetylglucosamine ( NAG ) and N - acetylmuramic acid ( NAM ) . Attached to the N - acetylmuramic acid is a peptide chain of three to five amino acids . The peptide chain can be cross-linked to the peptide chain of another strand forming the 3D mesh - like layer . Peptidoglycan serves a structural role in the bacterial cell wall , giving structural strength , as well as counteracting the osmotic pressure of the cytoplasm . A common misconception is that peptidoglycan gives the cell its shape ; however , whereas peptidoglycan helps maintain the structural strength of the cell , it is actually the MreB protein that facilitates cell shape . Peptidoglycan is also involved in binary fission during bacterial cell reproduction . </P>
bacterial cell walls are made rigid by the presence of
Peptidoglycan , also known as murein