Enzymes Lab
Name____________________________________ Date______
NYA Biology
Objective: To understand the functioning of enzymes in living organisms.
Introduction: Catalase is an enzyme found in both plants and animals. The purpose of this enzyme is to
destroy hydrogen peroxide, which is a by-product of normal reactions in the cell, but which can be damaging
to cells in high concentrations. Catalase causes the breakup of this substrate to occur several thousand times
faster than it would on its own. This reaction releases water and oxygen gas, which are harmless to the cell.
The reaction:
H2O2

H2O
+
O2
Pre-Lab Questions: Answer on a separate sheet of paper
1. Read section 2.4 in your textbook and make a vocab list of the bolded terms in your own words
2. Label the reactants and products on the reaction above.
3. Draw a graph of the following situation: Reactants have energy of 48kJ. Activation energy is100kJ,
final energy is 96kJ. Does this reaction absorb energy or release energy overall?
4. Add another line to your graph showing how it would differ in the presence of an enzyme.
5. Explain how enzymes work and why we need them. Use the term “substrate” in your answer
6. Potatoes are very high in the enzyme catalase. What do you think will happen when we add a chunk
of potato to hydrogen peroxide (H2O2)? (You need to read the introduction above to answer this)
7. What would happen to you if the catalase in your cells stopped working?
8. List several types of conditions that affect how well an enzyme functions.
Procedure part A: Observing the action of catalase
1. Put one piece of potato into a clean test tube.
2. Pour 2mL of the hydrogen peroxide into the test tube with the potato.
3. Observe the reaction in the test tube. Record your results in table 1
Estimate the rate of the reaction (as measured by how rapidly the solution bubbles) on a scale of 0-5.
(0=No reaction,1=Slow, 5=Very Fast) We will use this reaction as a control and say that it
proceeded at a rate of 4. You can compare the rest of your results to this one.
4. Remove the potato from the test tube and place in a clean test tube.
5. In the test tube with the liquid, add another piece of potato.
6. In the tube with the original potato chunk, add 2mL of hydrogen peroxide
TABLE 1
Treatment
0-5 reaction rate
Potato + H2O2
4
Used H2O2 + new potato
Why did this
happen?
Part B: Effect of Temperature on Enzyme Activity
1. Label 3 test tubes H (hot), C (cold), and R (room temperature).
2. Place one cube of potato into each test tube.
3. Put enough distilled water in each test tube to just cover the potato cube
Used potato + new H2O2
4. Divide and conquer for this step! Place the test tube labeled H into the hot water bath, the test tube labeled
C into the cold water bath, and the test tube labeled R temperature in the test tube rack on your table. Leave
each of the tubes in place for 3 minutes. While you wait, complete your hypothesis and step 4.
What is your hypothesis about what will happen when H2O2 is added to each tube? WHY do you expect to
see these results?
Hot -
Cold -
Room Temp -
4. Record the temperature of the two water baths and the air in Table 2.
5. Empty the excess water from the tube into the sink, making sure to keep the potato in the tube
6. Add 2 ml of Hydrogen peroxide into each tube.
7. Observe the test tube for one minute and record the relative rate for each tube in Table 2.
TABLE 2 – Reaction rate of catalase at various temperatures
Temperature (Degrees C)
Reaction Rate (0-5)
Hot
Cold
Room Temp
3
2
1
0
Reaction Rate
4
5
GRAPH 1: Relative Reaction Rates of Potato Catalase as a Function of Temperature
Temperature (Degrees Celsius)
1. What is the optimal temperature for the activity of potato catalase? ______________________
2. WHY is this the optimum temperature? What happens to the enzyme above this temperature? Below it?
3. Would your answer to #5 be the same for every enzyme in every organism? Why or why not?
Part C: Design your own experiment – complete this in your lab notebook following the “Biology
Experimental Protocol”
Materials: all standard lab equipment is available. Additional materials available on request.
Potato
Calf liver (contains animal catalase)
Hydrogen peroxide
Saliva (a source of an enzyme called salivary amylase which breaks starch into sugar)
Starch solution
Saltine Crackers
Starch Test Solution
Sugar test solution
Ethanol (alcohol)
Hydrochloric acid
Water baths of various temperatures
Sodium Hydroxide (base)
pH testing paper
Thermometer
Experimental Questions: using the materials available, what are three experimental questions you could ask
that would allow you to learn something more about enzymes and their behavior?
1.
2.
3.
Question: Discuss questions with your group and pick 1 to test. Pick one that is interesting and feasible.
Check it with Ms. Lauerman.
Hypothesis: What do you think is the answer to your question and why do you think this based on your
knowledge of enzymes and/or proteins?
Procedure: Write the procedure you will carry out to test your hypothesis. Make sure you are specific
enough that someone else could follow your procedure
Data Table: Construct a table where you can record your data
-*-* STOP HERE – You must have your procedure checked by Ms. Lauerman before moving on -*-*
Graph your results: Don’t forget to label the axes and give your graph a title.
Biology Lab Report Guidelines
Overall Expectations: _____/5
▪ Writing is clear and concise.
▪ Spelling and grammar are correct
▪ Sections of lab are clearly labeled
▪ Lab has a title of your own devising
Introduction: _____/10 This section should describe the goal(s) or purpose of the experiment. The
introduction should also include background information on the question being addressed by the experiment
and a hypothesis.
▪
▪
▪
▪
▪
▪
▪
The goal/purpose of the experiment is clearly stated
Detailed, pertinent background knowledge is included to explain what is already known.
The experimental question(s) are clearly stated
Question(s) are connected to and expands on background knowledge
Prediction(s) in the form of a hypothesis is clearly stated
Prediction(s) is testable and answers the question.
Reasons for prediction(s) are explained thoroughly and display sound logic
Methods: _____/10 This section should include the means that were taken to run the experiment.
▪
▪
▪
▪
Explanation is thorough enough that a reader can follow what has been done.
Methods are presented in paragraphs, in sentence form, in the proper order
All necessary materials are mentioned in the methods (but not listed)
Clearly labeled diagrams and/or pictures are included to illustrate the set-up.
Results: _____/10 This section should include collected data and observations. This section includes all
data manipulation. This may be done through mathematical relationships, graphs, and statistical analysis.
Lastly, this section includes an explanation (in words) of what the results were
Raw Data Raw data should be presented in an appropriate form – usually data table(s).
▪ Data table is labeled with titles and units.
▪ All numbers have units as needed
Data Manipulation
▪ All work is shown for any calculations
▪ graphs and figures are included as needed and labeled with numbers (Figure 1, 2, 3, etc.)
▪ figures have titles (with figure number), labels and units on axes
▪ figures make sense (numbers, axis choices, standard ascending/descending choices, reasonable
intervals, choose type of graph line/scatter plot/bar graph appropriately ).
▪ Figures should not break across the page.
Summary Explanation of Data
▪ Explain in words what you found in paragraph form
▪ No conclusions are drawn from the data in this section
Discussion: _____/15 This section is a thorough analysis of the entire lab, including an analysis of the data,
a discussion of the efficacy of the experimental design, and a summary of what was found in the lab with
regard to the initial goals.
For each part of the lab (if it contains multiple parts) you need two paragraphs:
Paragraph 1 – Data Analysis
▪ State whether your hypothesis was or was not supported. Use specific evidence from your data to
explain why your hypothesis was or was not supported
▪ Bring in outside material from textbook, class notes, or other sources to confirm that your results
make sense in the context of your knowledge about the subject. If your results don’t make sense, you
need to explain this as well. You should cite specific passages from your sources in correct APA
format (use www.bibme.org to help)
▪ Recognize where your data is limited – do not make claims that you cannot support
▪ Bring in outside material from textbook or reading or background knowledge to confirm “that this
makes sense.”
Paragraph 2 - Efficacy and Error
▪ Describe how effective your procedure was – did it effectively answer the question? Why?
▪ Explain any changes you made to the procedure or data collection during the lab and why you did
this.
▪ Describe two sources of error in the experiment. For each source of error
a. Describe the source of error
b. Describe how the source of error affected your results
c. Describe what you would do differently if you did this again to correct this source of
error
Conclusion: _____/5
▪ Restate the overall purpose of the lab and state whether you achieved this purpose
▪Include relevant “take home” learning about the topic at hand
▪ Write two additional experimental questions that you could answer to build on your work in this
experiment.
▪Include why the finding is important (to science and/or “real life”)
TOTAL ________/55