Enzymes are proteins found in plants or animals that cause or change the speed of chemical reactions. There are many different kinds of enzymes. Each enzyme has a specific shape, which allows it to help put together or break apart chemicals.
It is believed that enzymes act like a holder into which molecules fit like puzzles pieces. Some enzymes, like the one shown in the diagram, receive a single molecule, and then the enzymes bends or twists the molecule causing it to break apart. The diagram shows one molecule entering the enzyme and two separate molecules exiting. Of course this is a simple description for a much more complicated reaction.
Another type of enzyme receives separate molecules that join and leave as a single molecule. The diagram is a model of this combination reaction. Notice that it looks like the reverse of the decomposition diagram, only in reverse.
When the separate or single parts leave an enzyme, the enzyme is then free to be used again. This entire cycle happens so fast that a single enzyme can make about 1,000 changes per second or even faster.
Since enzymes are used over and over and work so fast, it only takes a small number of enzymes to cause form can thousands of chemical reaction every second. Eventually the enzymes wear out and the cells of the living organism (plant or animal) make new ones.
Enzymes cause both desired and undesired changes in food. For example, they are responsible for color, flavor, and texture changes as fruits and vegetables ripen. But, they also cause the foods to continue to ripen and eventually rot.
Enzymes are used to make meat more tender. Meats are “tough” because of the presence of the tough, insoluble protein collagen. Meat tenderizers contain enzymes that digest (decompose- break apart) collagen molecules.
For a model of how a catalyst puts molecules together, see CATALYST.
References:
Book
Janice VanCleave’s Food and Nutrition , 1999, John Wiley and Sons
Chapter 19 “Changers: The Affects of Enzymes on Food.” pages 139-147
Web Page
VanCleave, Janice. “Enzymes.”
Enzymes. 28 August 2009. Web. (Date you accessed the information) <http://scienceprojectideasforkids.com/2010/enzymes/>
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