How Enzymes Work: Investigating their specificity and susceptibility to environmental factors using Jell-O.
In this biology lab, students will use pineapple juice as an enzyme and Jell-O as a substrate to illustrate an enzyme/substrate complex. The initial guided procedure will allow students to discover that the processing of food, specifically canned pineapple, will denature the enzymes and render them useless. The lab extension questions allow students to design and conduct two additional investigations that focus on the behavior, function and the effect that environmental factors have on enzyme activity. The environmental factors that students can explore include: temperature, pH, microwave radiation and detergents.
1. This lab activity is designed for students to gain a general understanding of the characteristics of enzymes, their function and susceptibility to denaturing when exposed to a variety of environmental factors.
2. This lab activity is designed for students to develop inquiry skills by designing and conducting multiple investigations to answer guided questions and then communicate their findings with the class.
1. Enzymes are proteins that are specific and they do almost all the work within a cell.
2. Enzymes are not used up or changed when breaking down a substrate and can perform the same action over and over very quickly.
3. Under certain conditions, enzymes are denatured. This happens when the protein molecule loses its proper shape and can no longer function.
Context for Use
Resource Type: Activities:Lab Activity
Grade Level: High School (9-12)
Description and Teaching Materials
Students are given a copy of the lab to read before they come to class. They are asked to each write down a few of their ideas as to what factors may cause Jell-O not to set. Students should be organized into groups of 2-3.
Students will begin day 1 by performing the guided procedure of exposing pre-made Jell-O cubes to pineapple juice from two different sources: fresh versus processed. While observing for 30 minutes and collecting data at 5-minute intervals, student groups will choose two additional questions, from the questions provided, to investigate. Student groups decide on a procedure for each question and get teacher approval before they are allowed to experiment. Essentially the next two lab days, students are conducting their two investigations, collecting data and organizing their results to share with their classmates.
Reflections and Discussion Questions: Students continue to work in their groups to answer the questions provided at the conclusion of the investigations.
Final Assessment: Individually, students write a summary of their newfound understanding of enzymes, how they work and factors that affect their activity. They need to be specific and may even include a labeled diagram in their explanation.
(Initial Guided Lab):
Prepared 2-3 cm Jell-O Brand gelatin cubes (4 cubes per group)
Shallow dish or pan (Petri dish)
Fresh Pineapple juice
-Prepared by pureeing fresh pineapple in a blender. The puree should be strained through cheesecloth to separate the pulp from the juice.
Canned Pineapple juice
-Prepare as directed for fresh pineapple juice.
(Additional Materials Available to Students for their two further investigations):
Prepared Hot Knox Gelatin
(Stir 2 envelopes of KNOX unflavored gelatin into 800 ml of hot water) - enough for 3 classes, store in a warm water bath.)
Jell-O Brand Gelatin (can be used to prepare gelatin cubes)
Ice water bath
Test tubes and rack
pH testing paper
Razor Blade or Knife for cutting fruit
A variety of fruits:
Pineapple (fresh, frozen and canned), Apples, Grapes, Strawberries, Kiwi, Orange, Papaya, Fig, other...
Student Handout for Fruity Enzymes Lab Investigation (Microsoft Word 38kB Aug25 09)
Lab Adapted from the following References:
School Improvement in Maryland; "Pineapple/Jell-O Lab," Regulation of Enzyme Activity.
Access Excellence -Activities Exchange; "Enzyme Labs Using Jell-O" by Anne McDonald and Michael O'Hare.
AP & Regents Biology; "Lab 8: Pineapple Enzymes and Jell-O Molds" by Kim B. Foglia. 2005-2006
Teaching Notes and Tips
Preparing gelatin: Stir two envelopes of KNOX unflavored gelatin into 800 ml of hot water. Store it in a warm water bath so it will pour easily.
If making Jell-O gelatin cubes, follow the directions for making "Jigglers" on the box but try reducing the amount of water used and pour in a smaller pan to make "chunkier" cubes.
When using canned pineapple, the chunky style may work best. Frozen pineapple may be substituted for the fresh pineapple if fresh is unavailable. Freezing does not denature the enzyme. Frozen fruit juice concentrate may also be interesting to investigate.
Remind students to not cross-contaminate anything during the course of their investigations. This may seem obvious but razor blades, blenders and equipment should be kept clean.
The name of the proteolytic enzyme (an enzyme that digests proteins) found in fresh pineapple is bromelain. (It is most abundant in the pineapple's stem.) Bromelain not only degrades the tough fibers in meat and the gelatin in Jell-O, it also eats away at the human tongue and skin. This same enzyme is found in other tropical fruits and is extracted and sold in products such as Schilling's Meat Tenderizer. Besides using powdered bromelain to tenderize meat, it may also be used to treat inflammation, swelling, indigestion and even excessive blood clotting.
*In the past, we have spent little time in 10th grade biology demonstrating how enzymes function. We discuss enzymes, give a few examples and try to emphasize their importance to cell functioning but I think that without a visual example of how an enzyme works, I question authentic student understanding. With the new revised MN standards, macromolecules and specifically enzymes are identified as benchmarks. I am hoping that by incorporating this lab activity, students will better understand the role and function of enzymes.
Each investigation needs to include the following:
b. Reason for your Prediction:
d. Data Table with the Results
e. Share your results with the class.
Reflections and Discussion Questions:
1. Clearly describe the results of your experiments. Provide a statement for what happened in each.
2. Clearly explain the results of your experiments. Why did you get the results that you did? Be specific!
3. What type of macromolecule is gelatin?
4. What substance contains the enzyme in this lab?
5. Identify the substrate in the lab(s)?
6. What does it mean when an enzyme "denatures?"
7. Are enzymes specific? Explain.
8. Out of curiosity, what are some other food items we eat that contain gelatin? You may need to research this!!
9. Create 1 new testable question regarding enzymes that if given enough time, you would want to investigate.
Individually, write a summary of your newfound understanding of enzymes, how they work and factors that affect their activity. Be specific. You may even want to include a labeled diagram in your explanation.
22.214.171.124.1 Scientific Inquiry: designing and conducting an experiment.
126.96.36.199.1 Factors such as pH and temperature affect cell processes.
188.8.131.52.2 Proteins, specifically enzymes, allow cells to function.