written by: J.Sace•edited by: Wendy Finn•updated: 2/13/2010
A science experiment that demonstrates how enzymes contained in pineapple and liquid detergent work in turning a semi-solid gelatin product into its liquid form. In this experiment, students will be able to learn how enzymes work.
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Enzymes are special kind of proteins that speeds up the rate of chemical reactions in biological systems. They are found in all living things: plants, animals, bacteria, and fungi. They make life possible on earth because they are involved in vital life processes such as digestion, energy production, reproduction, and many more.
Knowledge of enzymes is important for students because it enables them to understand more complex processes in biology as they advance in their studies. Below is the plan for a science project, “How do enzymes work?" that students will surely enjoy. This experiment is good for grade 9-10 students.
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Materials Needed for this Fun Science Experiment
2 small glass containers
1 ripe, fresh pineapple
Gelatin powder (any brand and any color)
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Procedure for this Fun Science Experiment
Put 1 teaspoon of gelatin powder in each of the glass containers. Pour each container ½ full of hot water to dissolve the gelatin powder. Using a spoon, stir the solution until the gelatin powder is completely dissolved. Let the gelatin product in the containers cool for a while and then refrigerate them. If the gelatin products are already firm in texture, they are ready for use in the experiment.
Using the knife, peel off the skin of the fresh pineapple. (Note: Don’t use pineapples sold in tin cans because they contain less effective enzymes). After removing the pineapple’s skin, cut a thin slice from it.
Place the thin slice of pineapple on the top of the gelatin product in one of the containers. Put several drops of liquid detergent on the second container.
Wait for several hours until you begin to see changes on the gelatin.
Record all your observations.
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What will students observe on the gelatin products?
The students will notice that the thin slice of fresh pineapple begins to sink at the bottom of the container. The pineapple sinks because the gelatin product becomes more liquid. The gelatin product with liquid detergent is also liquefied.
The teacher then asks the students:
"What may have caused the gelatin to liquefy that way?"
"What do the pineapple and liquid detergent contain that can cause gelatin product to become liquid?"
Discuss with the students the concept of enzymes and how they work using the results of this experiment. Explain that the pineapple and the liquid detergent contain enzymes that break down bonds that bind the molecules in the gelatin together.
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How do enzymes work on the gelatin products?
The fresh pineapple contains the enzyme “bromelain" that removes the thickening properties of the gelatin product. Bromelain is a protease enzyme capable of digesting proteins. It is an enzyme found on the pineapple fruit and its relative species. Gelatin is made up of protein so it can be broken down by the bromelain enzyme in the pineapple. Gelatin is manufactured by partial hydrolysis of collagen, a connective tissue of animals.
Like the pineapple, the liquid detergent also contains proteases that break down proteins in the gelatin. Manufacturers of liquid detergent put proteases in their product because these proteases break down protein-based stains on our plates when we wash our dishes.