ABSTRACT
Chemically, carbohydrates contain carbon (carbo), and hydrogen and oxygen in the same proportion as in water (hydrate). Combining atoms of carbon, hydrogen, and oxygen forms a simple carbohydrate or sugar molecule with the general formula C 6 H
12 O
6 , although the number of carbon can vary from three to seven. Six-carbon
sugars are also referred to as hexoses. Accordingly, three-carbon sugars are trioses, fourcarbon sugars are tetroses, five-carbon sugars are pentoses, and seven-carbon sugars are heptoses. Of these varieties, the hexose sugars interest nutritionists the most. In these molecules, atoms of carbon (C), oxygen (O), nitrogen (N), and hydrogen (H) are linked by chemical bonds. Atoms form molecules in ways that satisfy the bonding requirement of each atom. For example, as shown in Figure 2.1, each carbon atom has four binding sites that link to other atoms, including carbons. Carbon bonds not linked to other carbon atoms accept hydrogen (with one binding site), oxygen (with two binding sites), or an hydrogen-oxygen combination (OH) referred to as hydroxyl.
