Starch: Amylopectin and Amylose

Starch is a carbohydrate commonly found in nature and one of the primary sources of food energy for human beings. It is regularly eaten in the form of wheat, rice, potatoes, and other staple foods cultivated throughout the world. Alongside fiber and sugar, starch is one of the three main categories of carbohydrates. Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diets, and is contained in large amounts in staple foods like wheat, potatoes, maize (corn), rice, and cassava (manioc). Pure starch is a white, tasteless and odorless powder that is insoluble in cold water or alcohol. It consists of two types of molecules: the linear and helical amylose and the branched amylopectin. Depending on the plant, starch generally contains 20 to 25% amylose and 75 to 80% amylopectin by weight. Glycogen, the glucose store of animals, is a more highly branched version of amylopectin. In industry, starch is converted into sugars, for example by malting, and fermented to produce ethanol in the manufacture of beer, whisky and biofuel. It is processed to produce many of the sugars used in processed foods. Mixing most starches in warm water produces a paste, such as wheatpaste, which can be used as a thickening, stiffening or gluing agent. The greatest industrial non-food use of starch is as an adhesive in the papermaking process. Starch solution may be applied to certain textile goods before ironing, to stiffen them. Problems: Which of the following is not a polymer? A) starch B) DNA C) glucose D) RNA Starch is composed of ________. A) unbranched amylopectin and branched amylose B) branched amylopectin and branched amylose C) branched amylopectin and unbranched amylose D) unbranched amylopectin and unbranched amylose #polymers #amylopectin #starch #amylose #sugar #carbohydrates #biology #biochemistry