Editing Polymer backbone (section)

=== Carbohydrates ===
Carbohydrates arise by condensation of [[monosaccharide]]s such as [[glucose]]. The polymers can be classified into [[oligosaccharide]]s (up to 10 residues) and [[polysaccharide]]s (up to about 50,000 residues). The backbone chain is characterized by an ether bond between individual monosaccharides.  This bond is called the [[Glycosidic bond|glycosidic linkage]].<ref>{{Cite journal|last=Buschiazzo|first=Alejandro|year=2004|title=Crystal structure of glycogen synthase: homologous enzymes catalyze glycogen synthesis and degradation|journal=The EMBO Journal |volume=23|issue=16|pages=3196–3205|doi=10.1038/sj.emboj.7600324|pmc=514502|pmid=15272305}}</ref> These backbone chains can be unbranched (containing one linear chain) or branched (containing multiple chains). The glycosidic linkages are designated as [[Anomer|''alpha'' or ''beta'']] depending on the relative [[stereochemistry]] of the [[anomer]]ic (or most [[oxidized]]) carbon. In a [[Fischer projection|Fischer Projection]], if the glycosidic linkage is on the same side or face as carbon 6 of a common biological saccharide, the carbohydrate is designated as ''beta'' and if the linkage is on the opposite side it is designated as ''alpha''. In a traditional "[[Cyclohexane conformation|chair structure]]" projection, if the linkage is on the same plane (equatorial or axial) as carbon 6 it is designated as ''beta'' and on the opposite plane it is designated as ''alpha''. This is exemplified in [[sucrose]] (table sugar) which contains a linkage that is ''alpha'' to glucose and ''beta'' to [[fructose]]. Generally, carbohydrates which our bodies break down are ''alpha''-linked [[Glycogen|(example: glycogen)]] and those which have structural function are ''beta''-linked (example: [[cellulose]]).<ref name=Voet16 /><ref>{{cite book |vauthors=Bertozzi CR, Rabuka D |chapter=Structural Basis of Glycan Diversity |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK1955/ |veditors=Varki A, Cummings RD, Esko JD, et al |title=Essentials of Glycobiology |publisher=Cold Spring Harbor Laboratory Press |year=2009 |isbn=9780879697709 |edition=2nd |url=https://www.ncbi.nlm.nih.gov/books/NBK1908/ |pmid=20301274}}</ref>