Editing Polysaccharide (section)

==Structural polysaccharides==
[[File:Structural polysaccharides.png|thumb|upright=1.25|Some important natural structural polysaccharides]]

=== Arabinoxylans ===
[[Arabinoxylan]]s are found in both the primary and secondary cell walls of plants and are the copolymers of two sugars: [[arabinose]] and [[xylose]]. They may also have beneficial effects on human health.<ref>{{cite journal | title = Arabinoxylans and human health | vauthors = Mendis M, Simsek S | journal = Food Hydrocolloids | volume = 42 | pages = 239–243 | date = 15 December 2014 | doi = 10.1016/j.foodhyd.2013.07.022 }}</ref>

=== Cellulose ===
{{Main|Cellulose}}

The structural components of plants are formed primarily from cellulose. Wood is largely cellulose and [[lignin]], while [[paper]] and [[cotton]] are nearly pure cellulose. Cellulose is a [[polymer]] made with repeated glucose units bonded together by ''beta''-linkages.  Humans and many animals lack an enzyme to break the ''beta''-linkages, so they do not digest cellulose.  Certain animals, such as [[termite]]s can digest cellulose, because bacteria possessing the enzyme are present in their gut. Cellulose is insoluble in water. It does not change color when mixed with iodine. On hydrolysis, it yields glucose. It is the most abundant carbohydrate in nature.<ref>{{Cite book |last1=Bhardwaj |first1=Uma |url=https://books.google.com/books?id=93yeKr9W9TwC |title=Biochemistry for Nurses |last2=Bhardwaj |first2=Ravindra |publisher=Pearson Education India |isbn=978-81-317-9528-6 |language=en}}</ref>

=== Chitin ===
{{main|Chitin}}
Chitin is one of many naturally occurring [[polymer]]s. It forms a structural component of many animals, such as [[exoskeleton]]s. Over time it is [[bio-degradable]] in the natural environment. Its breakdown may be catalyzed by [[enzyme]]s called [[chitinase]]s, secreted by microorganisms such as [[bacteria]] and [[fungi]] and produced by some plants. Some of these microorganisms have [[Chemoreceptor|receptors]] to simple [[sugar]]s from the decomposition of chitin. If chitin is detected, they then produce [[enzyme]]s to digest it by cleaving the [[glycosidic bond]]s in order to convert it to simple sugars and [[ammonia]].<ref>{{Cite book |last=Moussian |first=Bernard |title=Targeting Chitin-containing Organisms |date=2019 |chapter=Chitin: Structure, Chemistry and Biology |chapter-url=https://pubmed.ncbi.nlm.nih.gov/31102240/ |series=Advances in Experimental Medicine and Biology |volume=1142 |pages=5–18 |doi=10.1007/978-981-13-7318-3_2 |issn=0065-2598 |pmid=31102240|isbn=978-981-13-7317-6 }}</ref>

Chemically, chitin is closely related to [[chitosan]] (a more water-soluble derivative of chitin). It is also closely related to cellulose in that it is a long unbranched chain of [[glucose]] derivatives. Both materials contribute structure and strength, protecting the organism.<ref>{{Cite journal |last1=Merzendorfer |first1=Hans |last2=Zimoch |first2=Lars |date=December 2003 |title=Chitin metabolism in insects: structure, function and regulation of chitin synthases and chitinases |url=https://pubmed.ncbi.nlm.nih.gov/14610026/#:~:text=Chitin%20is%20one%20of%20the,matrices%20lining%20the%20gut%20epithelium. |journal=The Journal of Experimental Biology |volume=206 |issue=Pt 24 |pages=4393–4412 |doi=10.1242/jeb.00709 |issn=0022-0949 |pmid=14610026|bibcode=2003JExpB.206.4393M |s2cid=27291096 }}</ref>

=== Pectins ===
[[Pectin]]s are a family of complex polysaccharides that contain 1,4-linked α-{{sc|D}}-galactosyl uronic acid residues. They are present in most primary cell walls and in the nonwoody parts of terrestrial plants.<ref>{{Cite journal |last=MOHNEN |first=D |date=2008 |title=Pectin structure and biosynthesis |url= |journal=Current Opinion in Plant Biology |volume=11 |issue=3 |pages=266–277 |doi=10.1016/j.pbi.2008.03.006 |pmid=18486536 |bibcode=2008COPB...11..266M |issn=1369-5266}}</ref>