Editing Cell wall (section)

===Algae===
[[File:Diatoms.png|thumb|right|[[Scanning electron microscope|Scanning electron]] [[micrograph]]s of [[diatom]]s showing the external appearance of the cell wall]]
Like plants, algae have cell walls.<ref>{{cite web | last = Sengbusch | first = Peter V. | name-list-style = vanc | date = 2003-07-31 | url = http://www.biologie.uni-hamburg.de/b-online/e26/26d.htm | title = Cell Walls of Algae | archive-url = https://web.archive.org/web/20051128095106/http://www.biologie.uni-hamburg.de/b-online/e26/26d.htm | archive-date = November 28, 2005 | work = Botany Online | publisher = biologie.uni-hamburg.de | access-date = 2007-10-29 }}</ref> Algal cell walls contain either [[polysaccharide]]s (such as cellulose (a [[glucan]])) or a variety of [[glycoprotein]]s ([[Volvocales]]) or both. The inclusion of additional [[polysaccharide]]s in algal cells walls is used as a feature for algal [[taxonomy (biology)|taxonomy]].

* [[Mannan (polysaccharide)|Mannan]]s: They form microfibrils in the cell walls of a number of [[Marine (ocean)|marine]] [[green algae]] including those from the [[genera]], ''[[Codium]]'', ''[[Dasycladus]]'', and ''[[Acetabularia]]'' as well as in the walls of some [[red algae]], like ''[[Porphyra]]'' and ''[[Bangia]]''.
* [[Xylan]]s:
* [[Alginic acid]]: It is a common polysaccharide in the cell walls of [[brown algae]].
* [[Sulfonated]] polysaccharides: They occur in the cell walls of most algae; those common in red algae include [[agar]]ose, [[carrageenan]], [[porphyra]]n, [[furcelleran]] and [[funoran]].

Other compounds that may accumulate in algal cell walls include [[sporopollenin]] and [[calcium|calcium ions]].

The group of [[algae]] known as the [[diatom]]s [[Biosynthesis|synthesize]] their cell walls (also known as [[frustules]] or valves) from [[silicon dioxide|silicic acid]]. Significantly, relative to the organic cell walls produced by other groups, silica frustules require less energy to synthesize (approximately 8%), potentially a major saving on the overall cell energy budget<ref>{{Cite journal | doi = 10.1111/j.1469-185X.1983.tb00385.x | vauthors = Raven JA | year = 1983 | title = The transport and function of silicon in plants | journal = Biol. Rev. | volume = 58 | issue = 2| pages = 179–207 | s2cid = 86067386 }}</ref> and possibly an explanation for higher growth rates in diatoms.<ref>{{Cite journal | doi = 10.1093/plankt/12.6.1117 | vauthors = Furnas MJ | year = 1990 | title = ''In situ'' growth rates of marine phytoplankton : Approaches to measurement, community and species growth rates | journal = J. Plankton Res. | volume = 12 | issue = 6| pages = 1117–1151 }}</ref>

In [[brown alga]]e, [[phlorotannin]]s may be a constituent of the cell walls.<ref>{{cite journal | vauthors = Koivikko R, Loponen J, Honkanen T, Jormalainen V | title = Contents of soluble, cell-wall-bound and exuded phlorotannins in the brown alga Fucus vesiculosus, with implications on their ecological functions | journal = Journal of Chemical Ecology | volume = 31 | issue = 1 | pages = 195–212 | date = January 2005 | pmid = 15839490 | doi = 10.1007/s10886-005-0984-2 | url = http://users.utu.fi/veijor/project/2005JCE.pdf | citeseerx = 10.1.1.320.5895 | s2cid = 1540749 }}</ref>