Suzanne Kulcsar, age 13, of Gary, Ind., for her question:
What is cellulose?
Cellulose is one of the many great gifts to us from the plant world. We use it to build houses, to make clothes and draperies and to make sponges and paper, Cellulose plays a part in the making of safety glass paints and lacquers. It is used to make gunpowder and high explosives and does hundreds of jobs around a busy hospital, It helps to make photographic film and countless plastics. We eat it with all our vegetables and, though it gives us no nourishment, it does help us to digest other foods.
As a chemical, cellulose is closely related to sugar and rated as a carbohydrate, which means that it is a compound of carbon, hydrogen and oxygen. Each cellulose molecule is composed of six atoms of carbon, ten atoms of hydrogen and five atoms of oxygen. These molecules tend to string together in long chains called polymers. In the plant world, they form sturdy, fibrous tissues. Mixed with a plant cement called lignin, they form the woody fabric from which the cell walls are made.
The woody trunk of a tree is no more than dead cell walls. The living substance which once filled the cells has gone from all but the outer rim of the trunk. This gives you some idea of how tough cellulose can be. In the case of a woody trunk, it is sturdy enough to support a mighty tree. About 30 per cent of every plant is made from cellulose. It forms the boxy cell walls which support the stems, roots and foliage. We eat it along with every bite of salad or vegetable. Though cellulose is too tough for us to digest, it provides the bulk needed to start our digestive organs moving.
Sturdy as it is, this vital compound is made by the plant from air, water and sunshine. The first stage in its manufacture is photosynthesis, the magic sunshine recipe by which a green plant makes simple sugar. Throughout the sunlight hours, this simple plant sugar is made by the green chlorophyll in leaves and stems, Carbon dioxide is taken from the air and water from the soil. The atoms are re shuffled in some mysterious way to make molecules of sugar. Some of this sugar will be further processed to oils and fats and some will be processed to make proteins. Much of it will be used to make cellulose, for this substance is needed to make the walls for every new cell which the plant grows.
In the world of chemistry, cellulose has a million chores. The raw material is taken from cotton, wood and flax. Rope, cotton and linen are everyday materials made from almost pure cellulose. Many other materials are made by treating the raw cellulose with strong chemicals. To make rayon, for instance, cellulose is dissolved in strong chemicals and sprayed or drawn into fine, fibrous threads fbr weaving. Other chemicals mixed with chips of wood turn the cellulose into paper. Every different substance made from cellulose calls for a different recipe,