In this part of the site, we will describe the structure of starch.
As we stated in the basics page, starch molecules are made up of two different types of molecules. Amylose and Amylopectin.
Amylose, is a linear polymer which constitutes about 20% of ordinary starch. This groups in the polymer are arranged in a continuous but curled chain. Such as a coil of rope. (see link for 2d models) Amylose, contributes to starch by gelling property. The molecular weight this 40,000-400,000 amu. It is composed of glucose joined by hydrogen bonds between the oxygen atoms in the glucose.
Amylopectin is a huge, but compact molecule. There is a considerable amount of side-branching and these chains are similar to those in amylose But only 25 glucose units occur per chain. The average molecular weight of amylopectin is 3000 amu but there may be up to 300 interconnecting chains which can change molecular weight and be up to one million amu. Since amylose does the gelling property, amylopectin contributes high viscosity. These are also bonded by hydrogen bonds.
Click here to see 2d models of amylose and amylopectin Click here to see 3d models of amylose and amylopectin
