noun, plural: starches
A starch is a complex polysaccharide made up of a large number of glucose as monomeric units joined together by glycosidic bonds. Two types of molecules comprise a pure starch: amylose and amylopectin.
All plant seeds and tubers contain starch which is predominantly present as amylose and amylopectin. Plants use starch as a way to store excess glucose, and thus also use starch as food during mitochondrial oxidative phosphorylation. Plants store excess starch in amyloplasts, which are leucoplasts that function primarily in storing starch granules through the polymerization of glucose and in converting these reserves back into simpler sugars (e.g. maltose and glucose), especially when light is not available. Chloroplasts, pigmented organelles involved primarily in photosynthesis, are also capable of storing starch.
Starch has many commercial uses, such as in papermaking, as a food, in the production of commercial grape sugar, for stiffening linen in laundries, in making paste, in printing industry, in hydrogen production, etc.
Word origin: Old English stearc (“stark, strong, rough”)