Frank Lopez, 12, of Mentmore, N.M., for his question:

WHAT IS AN ENZYME?

Each human body has more than 1,000 different types of enzymes. Each kind performs one specific job. Without enzymes, we could not breathe, digest food, see or move any part of our bodies. Enzymes can also be found in plants. The entire process of photosynthesis in plants actually depends on enzyme action.

Enzymes are protein molecules that speed up chemical reactions in all animals and plants. Reactions would happen too slowly or not at all without enzymes, so it can be said that life wouldn't be possible without them.

Every living cell makes enzymes, but they are not alive. Enzyme molecules do their jobs by altering other plant or animal molecules. Enzymes actually act as catalysts and perform their functions a million times a minute.

Many enzymes have the job of breaking complex substances down into simpler ones. Others build complex compounds out of simple ones. Some remain in the cells where they were formed while others do their work elsewhere. The enzyme amylase, for example, is secreted by the pancreas and travels to the small intestine where it breaks down carbohydrates.

The name enzyme came from two Greek words meaning " in yeast'' since scientists who were investigating the subject in the 1800s did their work on reactions caused by yeast enzymes. It wasn't until 1926 that an American biochemist named James Summer isolated a pure enzyme in the form of crystals. In 1969 scientists created the first man made enzyme.

Enzymes are too small to be seen through even the most powerful microscope. But scientists know through research techniques their shapes and sizes. And they know just how the structure of any particular enzyme enables it to cause certain chemical reactions in other molecules.

Enzymes have many uses beside those of their natural functions in the body. A large number of manufactured products make use of enzymes. Some detergents, as an example, contain enzymes which break down protein matter, such as perspiration, that cause stains. Enzymes are also used in the manufacture of meat tenderizers, antibiotics, bread, cheese, coffee, vinegar, vitamins and many other items.

At some time in the future, scientists tell us, we will probably use enzymes to change raw sewage into useful products. And enzymes may also be used to turn spilled oil, that harms oceans and lakes, into food for sea plants.

Doctors use many medicines that contain enzymes to break up blood clots, clean wounds, relieve some types of leukemia and to check allergic reactions to penicillin.

Doctors also diagnose a number of diseases by measuring the amount of various enzymes that can be found in blood and other body fluids. Included in this are such diseases as anemia, cancer and leukemia. Some heart and liver ailments~can also be diagnosed this way.