Starch

Starch is a storage polysaccharide made of two related polymers of glucose: amylose and amylopectin. Starch grains form from successive layers of amylose and amylopectin laid down over time, visible microscopically as growth rings. Amylose is a linear, unbranched polymer of glucose units and makes up about 80% of starch by mass. Amylopectin is also a glucose polymer, but it carries occasional 1,6-glycosidic linkages in addition to the main chain's 1,4-linkages, and these extra linkages create branch points that give amylopectin its characteristic branched structure. This mixture of a compact linear polymer and a more open branched polymer allo …