Mrs. Busybody Story
The following is a very dramatic story to help students remember why enzymes are so special to the functioning of a cell. First tell them the actual definition as it relates to a chemical change while you write the definition on the board or overhead.
An enzyme is a special substance (protein ) that brings about (speeds up) a chemical change but does not change itself.
As you tell your story with as much flamboyance as you can generate, ask them to be listening for which character in the story would best represent the role of the enzyme.
Setting: Eastern Europe. The time is the mid 1800's. Life is different than today. People were born, lived and died in the same area. Families were large and extended. Travel and long distance communication were difficult. People within a community were dependent upon one another. Male and female roles were very established and traditional. Modern medicine was not around and people died at early ages and women often died during childbirth. People often married out of necessity rather than for love. This was a time before there were TV's, computers, microwaves, dry cleaners, fast foods, frozen foods, birth control, antibiotics, modern plumbing, women's lib, etc.
Plot: Mr. and Mrs. Schmidt are very concerned that Mildred, their "lovely" eldest daughter (one of 10 children) is not yet married and out of the house since another child is on the way. They decide to consult the town matchmaker Mrs. Busybody who makes it her business to know everyone else's business. In fact, her ears are "soooo" big that she makes it her business not only to know all her village's gossip but the gossip of the neighboring villages along the rail line. As a matchmaker arranging marriages, she will be paid for her services. If she can find a husband for Mildred there will be money in her pocket for the effort, so of course, she tells the Schmidts that she has just the man for their Mildred.
Since there are no "eligible" men in this town she takes the train the next day to another village to hunt up some fine man for Mildred. Any eligible man will do. And who should she find but Mortimer, who happens to be a 40 year-old man with six children whose wife has just died. Out of necessity he is in need of a wife and agrees to marry Mildred, sight unseen.
A wedding is arranged between Mildred and Mortimer. It is the day of the wedding and present at the wedding are Mom and Dad Schmidt, "lovely" Mildred, Mortimer and his six children, the justice of the peace, and of course, Mrs. Busybody, who is happiest of all. Mildred Schmidt and Mortimer Jones change their relationship and become Mr. and Mrs. Jones as they are united in heavenly matrimony and live happily ever after.
Now let's look at this a little closer. Mrs. Busybody is Mrs. Busybody before Mildred met Mortimer, Mrs. Busybody is Mrs. Busybody when she attends the wedding, and she is Mrs. Busybody three years later when she visits them when their child is born. If Mrs. Busybody had not set up Mildred and Mortimer their chance of getting together and changing their relationship may never have occurred.
Now which character in the story acts like an enzyme?
Some enzymes bring about "marriages" like Mrs. Busybody and some bring about divorces and cause things to split up. All enzymes are proteins and all enzymes are very, very picky (specific). Some enzymes even get assistance (coenzymes and vitamins) in order to accomplish their work.
Remember: A cell is a very busy place, and most of what it does is to move molecules around or change molecules into other kinds of molecules (chemical change) by either making smaller molecules bigger or bigger molecules smaller. Each and every one of these chemical changes occurring in a cell is controlled by one or more enzymes.