# Capsule --- A **capsule** is a structure that some [[prokaryote|prokaryotes]] have on the outside of the its [[cell wall#Cell Wall in Bacteria|cell wall]]. Capsules can protect the cell from things like the human [[immune system]] because phagocytes have a hard time identifying them as foreign due to the lack of identifying features. Capsules can also help the bacteria adhere to surfaces or to each other. ![[membrane, cell wall, capsule.png]] Some capsules are made up of some proteins, but are mostly made up of [[polysaccharide|sugars]]. "Glycocalyx" is an example of a sugary capsule. ## Biofilm **Biofilm** is a substance that results when [[capsule]]-having bacteria all glomb on to the surface they're on, as well as each other. The term refers to the bacteria as well as the gooed together capsules. ![[biofilm.png]] ## Capsules and the Immune System The ability to produce capsules does help the bacteria hide from the [[immune system]], because it essentially masks the presence of any [[complement protein]] that my have attached to it, effectively erasing any benefit from [[opsonin|opsinization]] the complement protein may have given it. Some capsules can even break down complement proteins that have attached to them. ___