On Food and Cooking

other atoms are attached. Some sugars are
simple molecules, while others are made from
two or more simple sugars joined together.
Glucose and fructose are simple
monosaccharides, while table sugar, or
sucrose, is a disaccharide made up of one
glucose and one fructose joined together.
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