Which two molecules are responsible for the structure of starch?

The structure of starch is primarily composed of two types of molecules: amylose and amylopectin.

Amylose is a linear polymer made up of glucose units connected by α-1,4-glycosidic bonds. This structure allows amylose to form helical shapes, which are important for storage and energy release in plants.

Amylopectin, on the other hand, is a highly branched form of starch, consisting of glucose units connected by both α-1,4-glycosidic bonds (in the chains) and α-1,6-glycosidic bonds (at the branch points). This branched structure makes amylopectin more soluble and allows for a faster rate of enzymatic breakdown, providing a quick source of energy to the organism.

Together, amylose and amylopectin make up starch, which serves as energy storage in plants and plays a critical role in human nutrition. The combinations of these two molecules are what give starch its unique properties, such as gelatinization and retrogradation, which are important in food preparation and processing.