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HOLIDAY SPIRIT REACTIONKatharine M. NoonanOakland High School 1023 MacArthur Blvd. Oakland, CA 94610 Type of Activity: Artwork, modeling, multicultural Target Audience: Biology, Advanced Biology This activity gives students a chance to work through and personalize their understanding of enzyme function. It is an opportunity to be creative and celebrate diversity. Background : Students should know that enzymes are protein catalysts which facilitate and control all of the chemical reactions of life. They should know that enzymes work by combining temporarily with their substrates to bring about favorable orientation for the formation of a chemical bond between the substrates. The idea that the function of an enzyme depends on its shape will emerge in this activity. Preparation time: Moderate. I make a large cardboard model of the HolidaySpirit molecule, the Love enzyme, and the separate substrates Holiday and Spirit to show students when I introduce the activity. I suspend the models from the ceiling for the duration of the activity. For students, you need to run off the directions for the project (follows), strips of 8" X 14" construction paper, scissors and paste, holiday paper of various types (the more diverse, the better). Ask students to bring in gold or white paint pens to label molecules cut out of non-solid paper. Markers for labeling. Class time needed for this activity is 2-3 class periods (shorter for more advanced groups). Activity Abstract: Students invent an enzyme and its substrates, using a holiday motif. They make a paper "story strip" to show how their enzyme catalyses the formation of its product. This gives the opportunity for one-on-one interaction between teacher and student as each student "acts out" his/her reaction for the teacher before pasting. Comparison of different student's work underscores the specificity of enzyme action and the importance of shape. Procedure: 1. Introduce the project using cardboard models to act out the Holiday Spirit Reaction. 2. For homework, ask students to think of a holiday molecule and an enzyme they would like to illustrate. If you have them, post some examples from previous years, or make a model story strip yourself, but emphasize that students should be creative and may celebrate their culture if they wish. You can decide how outrageous they may be. I have my limits. One year I had a drug-related reaction, which I graded for accuracy, but did not display. I had a Kevorkian enzyme catalyzing successful suicide molecules (I didn't post that one, either). 3 . As students work, move around the room admiring choices of holiday molecules, enzymes, paper, shapes (I had a turkey-shaped enzyme catalyzing ThanksGiving molecules one year.) Ask students to show the steps of the reaction for you. They should be able to do this and identify terms in their model before they are allowed to paste. 4. Display the different story strips. Students enjoy seeing each other's work and being recognized for their own creativity. 5. Lead a discussion about the assembled story strips. Ask if the enzyme from one strip could catalyze the reaction on a different strip. What determines the shape of an enzyme? What would happen if a molecule similar to the enzyme's substrate stuck onto the active site and didn't fall off? (Noncompetitive inhibition). What if something attached to the enzyme and distorted the shape of the active site? (allosteric inhibition). What if there were other molecules which, like the real substrates, could attach briefly to the active site, but fell away without forming the product? (competitive inhibition). Evaluation: Grade story strips for completeness and accuracy, neatness and creativity. HOLIDAY SPIRIT REACTION Enzymes are protein molecules that help other molecules (substrates) react together (or break apart). They have active sites which hold the substrates in position so that a chemical bond can form between them with less activation energy. The combination of an enzyme and its substrate is called an enzyme-substrate complex. Once the bond is made, the enzyme-substrate complex breaks up. The joined substrates (now called the product) leave the enzyme. The enzyme is now free to help another pair of substrates bond together. Let's visualize this process by making a model with a holiday motif. Our product will be HolidaySpirit (or any two-word holiday phrase you choose: HabariGani (Kwanzaa), FelizNavidad, ProsperousNewyear, MerryChristmas, HappyHanukkah, etc.). What is it that helps produce this holiday feeling for you? Love? Friendship? Peace? These things help create the holiday feeling but are not used up! Choose one (e.g. Love) to be your enzyme. Draw your combined enzyme and substrates to the right. This is the enzyme-substrate complex. Write the names you have chosen for the enzyme, and product on the drawing. Using your drawing as a pattern cut out 5 enzyme shapes of one color, and ten of each substrate shape using different colors. Obtain a 8" X 14" strip of construction paper and fold it into 4 frames. Arrange your shapes to illustrate the enzyme-catalyzed reaction. CHECK WITH YOUR TEACHER BEFORE YOU DO ANY PASTING OR PERMANENT WRITING. Write these captions below each frame, and put in arrows and labels to show substrates, enzyme, active site, and product. Frame 1: The substrates (e.g. Holiday and Spirit) can't react together by themselves. They bump together in ways that do not fit. They have too little or too much energy to form a bond. No HolidaySpirit (or your choice) is produced. Frame 2: The substrates attach to the active site on the enzyme (arrows). Frame 3: An enzyme-substrate complex is formed. Now the substrates (Holiday and Spirit) can react together. The (Love) enzyme holds them in the correct position. Frame 4: After the product (HolidaySpirit) forms, it falls off of the enzyme. The enzyme is then free to help new substrate molecules to form the product. (Show the product leaving the active site of the enzyme and 2 new substrates coming to the empty active site on the enzyme. Show several product molecules that have been made earlier by the enzyme.)
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