Name: ________________________________________________________________
Date: _____________________
Introduction to Enzymes Lab
Period: ___________________
Introduction:
In each individual cell of a human there are many chemical reactions taking place, performing the
necessary functions for being a large, complex, multicellular organism. Enzymes are biological catalysts. They
help to increase the rate of chemical reactions. Enzymes are most often proteins and their three-dimensional
shape is important to their catalytic activity. Because of their 3-D shape, enzymes are highly specific for the
reactions that they catalyze. In other words, they are highly specific for the substrates that they will act upon.
So any one "function", such as getting energy from a glucose molecule, actually involves many reactions, each
with a specific enzyme.
Hydrogen peroxide (H2O2) is a highly active chemical, often used for bleaching; it is sold as a 3%
solution in water. Within cells hydrogen peroxide is thought to be formed continually as a by-product of
biochemical processes. Because it is toxic, or poisonous, it would soon kill cells if not removed or broken
down immediately.
The chemical formula for this reaction is:
Catalase
2H2O2
 
 2H2O + O2
Procedure:
Test tube 1
Distilled water
1.
2.
3.
4.
Smash a piece of liver in a mortar and pestle
Place 2 mL of distilled water in a test tube.
Add a small piece of liver.
Note reaction in table.
Test tube 2 – Part A
3% hydrogen peroxide
1.
2.
3.
4.
Smash a piece of liver in a mortar and pestle
Place 2 mL of hydrogen peroxide in a test tube.
Add a small piece of liver.
Note reaction in table.
Test tube 2 – Part B
3% hydrogen peroxide
1. Pour out hydrogen peroxide but leave the liver from test tube 2.
2. Place 2 mL of hydrogen peroxide in a test tube.
3. Note reaction in table
Note the extent of the reaction
(No bubbles, a few bubbles, lots of bubbles)
Test tube #
Extent of reaction
Test tube 1
Test tube 2 – part A
Test tube 2 – part B
Questions:
1. Does the liver have a catalyst that reacts with peroxide? __________________________________.
2. What is the name of the catalyst found in the liver? __________________________________.
3. What is the substrate? __________________________________.
4. What are the products? __________________________________.
5. What are the bubbles? __________________________________.
6. What is the purpose of test tube 1? ___________________________________________________________
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7. What is the purpose of test tube 2 part b? ____________________________________________________
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8. Look at your results for the liver and hydrogen peroxide reaction. Assuming the reaction is complete,
what is this liquid composed of? What do you think would happen if you added more liver to this liquid?
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9. What cells in our bodies contain catalase? Why?
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