Editing Cell wall (section)

==Fungal cell walls==
[[File:Chitin.svg|thumb|Chemical structure of a unit from a [[chitin]] polymer chain]]
There are several groups of organisms that have been called "fungi". Some of these groups ([[Oomycete]] and [[Myxogastria]]) have been transferred out of the Kingdom Fungi, in part because of fundamental biochemical differences in the composition of the cell wall. Most true fungi have a cell wall consisting largely of [[chitin]] and other [[polysaccharide]]s.<ref>{{cite book | last = Hudler | first = George W. | name-list-style = vanc | date = 1998 | title = Magical Mushrooms, Mischievous Molds | location = Princeton, NJ | publisher = Princeton University Press | page = [https://archive.org/details/magicalmushrooms00hudl/page/7 7] | isbn = 978-0-691-02873-6 | url-access = registration | url = https://archive.org/details/magicalmushrooms00hudl/page/7 }}</ref> True fungi do not have [[cellulose]] in their cell walls.<ref name="Webster_2007">{{cite book | vauthors = Webster J, Weber RW | date = 2007 | title = Introduction to Fungi | url = https://archive.org/details/introductiontofu00jweb | url-access = limited | location = New York, NY | publisher = Cambridge University Press | pages = [https://archive.org/details/introductiontofu00jweb/page/n24 5]–7 }}</ref>

In fungi, the cell wall is the outer-most layer, external to the [[plasma membrane]]. The fungal cell wall is a matrix of three main components:<ref name="Webster_2007" />
* [[chitin]]: [[polymer]]s consisting mainly of unbranched chains of β-(1,4)-linked-[[N-Acetylglucosamine]] in the [[Ascomycota]] and [[Basidiomycota]], or poly-β-(1,4)-linked-[[N-Acetylglucosamine]] ([[chitosan]]) in the [[Zygomycota]]. Both [[chitin]] and [[chitosan]] are synthesized and extruded at the [[plasma membrane]].<ref name="Webster_2007"/>
* [[glucan]]s: glucose [[polymer]]s that function to cross-link [[chitin]] or [[chitosan]] polymers. β-glucans are glucose molecules linked via β-(1,3)- or β-(1,6)- bonds and provide rigidity to the cell wall while α-glucans are defined by α-(1,3)- and/or α-(1,4) bonds and function as part of the matrix.<ref name="Webster_2007"/>
* [[protein]]s: enzymes necessary for cell wall synthesis and lysis in addition to structural proteins are all present in the cell wall. Most of the structural proteins found in the cell wall are [[Glycosylation|glycosylated]] and contain [[mannose]], thus these proteins are called mannoproteins or [[Mannan (polysaccharide)|mannan]]s.<ref name="Webster_2007"/>