# Peptidoglycan --- **Peptidoglycan** is what the [[cell wall]] of [[bacteria]] is made up of. It is a mesh-like material made up of [[polysaccharide|polysaccharides]] chains, connected by short peptide strands. Due to it's rigid nature, it helps protect the bacteria by resisting [[osmosis|osmotic]] pressure. It also has features that allow the cell to gain vital magnesium ions. Human bodies recognize peptidoglycan as an [[antigen]] as we do not make it ourselves. If we get this in our bodies it can cause toxic shock. ![[peptidoglycan.png]] ## Structure The structure of peptidoglycan consists of alternating NAM and NAG sugars in chains, connected to each other in sheets by short peptide chains. The sheets are then layered on top of each other, also connected to each other by the peptide chains. The enzyme that connects the short peptide chains together, strengthening the whole structure is called **transpeptidase**. ![[transpeptidase.png]] Antibiotics such as [[antibiotics#Penicillin and Ampicillin|penicillin and ampicillin]] work by disabling transpeptidase and rendering the cell wall too weak, killing the bacteria. ## Pseudopeptidoglycan Instead of peptidoglycan, the cell wall of [[archaea]] is made out of "pseudopeptidoglycan", which is very similar to peptidoglycan, only the sugars are NAT and NAG instead. ___