Delphinidin

Carbohydrates are the most abundant organic compounds in nature. They include sugars and starches and contain C, H, and O in a ratio of, or close to a ratio of, 1C:2H:1O (CH2O). The number of CH2O units in a carbohydrate can vary from as few as three to as many as several thousand. There are three basic kinds of carbohydrates:
1. Monosaccharides are simple sugars with backbones consisting of three to seven carbon atoms. Among the most common monosaccharides are glucose (C6H12O6) and fructose, which is an isomer of glucose. Isomers are molecules with identical numbers and kinds of atoms, but with different structures and shapes. Accordingly, fructose, which is found in fruits, has the same C6H12O6 formula as glucose, but the different arrangement of its atoms gives it different properties, such as a slightly sweeter taste. Glucose, which is produced by photosynthesis in green plant cells, is a primary source of energy in the cells of all living organisms.

2. Disaccharides are formed when two monosaccharides become bonded together by dehydration synthesis. The common table sugar sucrose (C12H22O11) is a disaccharide formed from a molecule of glucose and a molecule of fructose; a molecule of water is removed during synthesis. The removal of a molecule of water during the formation of a larger molecule from smaller molecules is referred to as a condensation reaction. Sucrose is the form in which sugar is usually transported throughout plants and is also the form of sugar stored in the roots of sugar beets and the culms (stems) of sugar cane.

3. Polysaccharides are formed when several to many monosaccharides bond together. Polysaccharide polymers sometimes consist of thousands of simple sugars attached to one another in long, branched or unbranched chains or in coils. For example, starches, which are the main carbohydrate reserve of plants, are polysaccharides that usually consist of several hundred to several thousand coiled glucose units. When many glucose molecules become a starch molecule, each glucose gives up a molecule of water. The formula for starch is (C6H10O5)n, the n representing many units. In order for a starch molecule to become available as an energy source in cells, it has to be hydrolyzed; that is, it has to be broken up into individual glucose molecules through the restoration of a water molecule for each unit.

Throughout the world, starches are major sources of carbohydrates for human consumption—the principal starch crops being potatoes, wheat, rice, and corn in temperate areas, and cassava and taro in tropical areas. Cellulose, the chief structural polymer in plant cell walls, is a polysaccharide consisting of 3,000 to 10,000 unbranched chains of glucose molecules. Although cellulose is very widespread in nature, its glucose units are bonded together differently from those of starch, and most animals digest it much less readily than they do starch. Organisms that do digest cellulose, such as the protozoans living in termite guts, caterpillars, and some fungi, produce special enzymes capable of facilitating the breakdown of bonds between the carbons and the glucose units of the cellulose; the organisms then can digest the released glucose.