Living things put the sugars to two primary
uses. The first is the storage of chemical
energy. All life depends on sugars for the energy that fuels the activity of cells. This is why we have taste receptors that register the presence of sugars, and why our brain attaches pleasure to that sensation: sweetness is the sign of a food that can help supply our need for calories. The second major role for sugars is to provide building blocks for physical structures, especially in plants. The cellulose, hemicellulose, and pectin that give bulk and strength to plant cell walls are long chains of various sugars. The simple physical bulk of sugar is also useful to the cook, who can construct from it a variety of interesting textures.