POLYSACCHARIDES [Revision]
POLYSACCHARIDES (GLYCANS)
Carbohydrates composed of ten or more monosaccharide units or their derivatives (such as amino sugars and uronic acids) are generally classified as
Homopolysaccharides or Homoglycans
Starch
It is the storage form of glucose in plants, e.g. in potato, in grains and seeds and in many fruits. Starch is composed of two constituents viz. amylose and amylopectin.
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Amylose Amylose is a linear polymer of D-glucose units joined by α-1 → 4 glycosidic linkages |
Amylopectin Amylopectin is structurally identical to those of amylose (α-1→ 4 glycosidic linkages) but with side chains joining them by áα-1→ 6 ) linkages. |
Dextrin
Partial hydrolysis of starch by acids or áα-amylase) produces substances known as dextrins. These also occur in honey. All dextrins have few free aldehyde groups and can show mild reducing property. They are not fermented by yeast.