BCLN – Rev. July, 2015
BIO 12 UNIT 07: Enzymes
Name: ___________________
Project 1: Pineapple – The Jell-O Killer Lab
Potential Credits:
/30
Project Goals:
 to investigate how temperature affects enzyme activity
Instructions:
 Please read the Unit 7 Lessons in their entirety.
 Please read and complete the Pineapple - The Jell-O Killer Lab below,
Pineapple – The Jell-O Killer Lab:
BACKGROUND
In this lab, you will be investigating how various temperatures may affect the activity of the
enzyme, bromelain. Bromelain is an enzyme that is found in fresh and canned pineapple that
catalyzes the breakdown of proteins. Like all enzymes, bromelain itself is a protein and
therefore, must play by the rules of all proteins. If you recall from previous units, proteins can
only function when they obtain a particular three-dimensional structure. This structure is
determined by chemical bonds that form between the various amino acids within the protein.
However, these bonds can be disrupted and the protein denatured (rendered non-functional) by
various factors including pH changes and temperature changes. In this lab you will determine
the temperature at which bromelain becomes denatured by monitoring its ability to breakdown
the protein, gelatin, found in Jell-O.
Have you ever eaten Jell-O? Have you ever made Jell-O? Did you read the package directions
carefully? If so, you may have noted the warning to not add fresh or canned pineapple to the
Jell-O. Why? Because you will get a liquid mess instead of your favourite jiggly treat! That is
because when you add pineapple to Jell-O the bromelain in the pineapple digests and breaks
down the gelatin in the Jell-O. By subjecting pineapple juice to various temperatures then
adding it to Jell-O and observing the effect you will be able to determine the effect of
temperature on bromelain activity.
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BIO 12 UNIT 07: Enzymes
PURPOSE
To investigate the effect of temperature on bromelain enzyme activity.
HYPOTHESIS (5)
Please read the lab in its entirety and then write a hypothesis (If…then statement) on the effect of
temperature on bromelain activity. Write the hypothesis with respect to the effect on enzyme
activity and how this activity will be reflected in the solidification of liquidity of the Jell-O. In
other words, if the effect is greater enzyme activity how would you expect this to reflect upon the
solidification/liquidity of the Jell-O/Knox Gelatin solution?
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BIO 12 UNIT 07: Enzymes
MATERIALS
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fresh pineapple
knife
cutting board
blender
cheese cloth or very fine sieve
tape or elastic
bowl or measuring cup
20 small clear plastic cups (NO foam)
Jell-O or Knox Gelatin
water
pot
stove
thermometer
measuring cup
measuring spoons
timer
smartphone/camera
PROCEDURE
1. Label the plastic cups with water proof marker such that there are two cups each labeled
as 20 C, 30 C, 40 C, 50 C, 60 C, 70 C, 80 C, 90 C, and 100 C.
2. Prepare your fresh pineapple juice:
i.
Carefully remove skin and core from pineapple and dispose of.
ii.
Cut remaining pineapple into chunks.
iii. Place pineapple into blender and blend until smooth.
iv.
Place 3 layers of cheesecloth over bowl or measuring cup and secure in place with
tape or elastic, making sure that the cheesecloth is not pulled to tight (you want a
bit of a well for the blended pineapple to sit in).
v.
Carefully pour the blended pineapple into the cheesecloth, gather the cloth around
the blended pineapple and gently squeeze the fresh juice into the bowl or
measuring cup. 100 mL of fresh pineapple juice will be more than enough for the
lab.
3. Create a water bath to expose the enzyme to various temperatures of water.
i.
Take one cup each of the 20 C, 30 C, 40 C, 50 C, 60 C, 70 C, 80 C, 90 C,
and 100 C labelled cups and place 10 mL of pineapple juice into each of the
cups.
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BIO 12 UNIT 07: Enzymes
ii.
Heat 12 cups of water on the stove, constantly checking the temperature with the
thermometer. As the water reaches one of the desired temperatures scoop out 1
cup of water and immediately transfer into a small bowl or container and then
place the appropriately labelled cup with the pineapple juice into the water in the
bowl for 5 minutes (refer to Figure 1 below). CAUTION: make sure bowl can
withstand near boiling temperatures. Then set the cup with the heated juice aside,
pour the water out of the bowl and add the next temperature of water to the bowl.
Continue heating the various cups with juice to the appropriate temperature until
the 100 C temperature is reached, at this point carefully place the cup directly
into the pot of boiling water for 5 minutes (you may need to use tongs to hold it
upright). Again set aside the cup with the heated juice.
cup containing pineapple juice
bowl
water of desired temperature
Figure 1. Water bath set-up for heating the bromelain enzyme within the pineapple juice.
4. Prepare Jell-O almost according to directions (half the amount of water that the directions
call for) or prepare Knox Gelatin by mixing 1 package of Knox Gelatin with 90 mL of
boiling water and 30 mL of cold water. Place 10 mL of the Jell-O or Knox Gelatin
liquid into each one of the 20 C, 30 C, 40 C, 50 C, 60 C, 70 C, 80 C, 90 C, and
100 C labeled cups that have yet to be used (NOT THE ONES WITH THE HEATED
PINEAPPLE JUICE!). Allow to cool to room temperature.
5. Once the Jell-O or Knox Gelatin solutions have cooled, but have yet to solidify, add 3 mL
(~3/4 of a teaspoon) of the appropriately heated pineapple juice to each cup and mix
gently but thoroughly by swirling the cup.
6. Place all of the Jell-O/Knox Gelatin containing cups in the refrigerator overnight once
they have had the appropriately heated pineapple juice added to them.
7. Observe the Jell-O/Knox Gelatin the next day. Take pictures of each cup and record any
observations with respect to the solidification or liquidity of the gel. Present the findings
(photograph and observations) in a data table. Be sure to attach the data table to the lab.
8. Please complete the discussion section.
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BIO 12 UNIT 07: Enzymes
RESULTS (/10)
Please place your data table here or attach at the end of the lab. Regardless, please ensure that
the data table is accompanied by the figure title and legend provided below.
Table 1. The Effect of Temperature on Bromelain Enzyme Activity. Pineapple juice containing the enzyme
Bromelain was heated to the indicated temperatures for 5 minutes. 3 mL of the variously heated juices were then
added to a Jell-O or Knox Gelatin solution. The solution was then allowed to cool overnight and then its
solidification or liquidity was observed as an indication of the enzyme's activity and thus, of the effect of the
temperature on the enzyme's activity.
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BIO 12 UNIT 07: Enzymes
DISCUSSION (/15)
Please answer all questions in full sentences.
1. Based on your observations, what is the effect of temperature on bromelain activity? (/1)
2. Please explain how you arrived at your conclusion. (/2)
3. Was the enzyme denatured at any temperature? If so, at what temperature and how did
you determine this? (/1)
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BIO 12 UNIT 07: Enzymes
4. This experiment is lacking at least one control. What control might you add and why?
(/2)
5. Was your hypothesis supported by your data? Why or why not? (/3)
6. Please list one way that this experiment could be improved upon. (/1)
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BIO 12 UNIT 07: Enzymes
7. Please identify another factor, other than temperature, that may be investigated as to its
effect on enzyme activity. Please briefly describe how you would design a similar
experiment to investigate this factor. (/5)
Marking Guide:
 Hypothesis
 Results
/5
/10
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BIO 12 UNIT 07: Enzymes
 Discussion
Total =
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/15
/30