Name____________________________________________Period_______ENTRY #________
Liver Enzyme Lab
Background Information:
Enzymes:
Catalase is just one of many enzymes present in beef liver. This enzyme speeds up
the breakdown of hydrogen peroxide (H2O2) into liquid water (H2O) and gaseous
oxygen (O2). The chemical equation is written below:
H2O2
catalase
> H2O + O2
The gas product O2 is important because we will be able to observe the gas bubbles
forming if the chemical reaction is occurring. In this lab, we will be examining how
temperature change can affect the catalase enzyme’s function.
Extra: Ever get a cut and have hydrogen peroxide poured on the wound? It
bubbles up near the wound—that’s because you have catalase in your cells
too! Catalase is helpful because hydrogen peroxide is very toxic to cells. So
why do we pour hydrogen peroxide on the cut in the first place? Because we
are trying to kill bacteria that may have gone inside when the skin barrier
was broken (many harmful bacteria do NOT have the catalase enzyme)
Temperature:
At the molecular level, temperature is how fast molecules move. You can imagine
the molecular world as a place where molecules are constantly whizzing past each
other, occasionally bumping into one another. At a higher temperature, molecules
are moving faster.
--------------------------------------------------------------------------------------------Purpose:
The purpose of this lab is to determine the effects of temperature on the function
of the catalase enzyme.
Hypothesis:
1) Predict the amount of bubbling that you will see after placing the liver in
different temperature water baths. State your prediction as a hypothesis that
you can test.
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Name____________________________________________Period_______ENTRY #________
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Procedure:
(What follows below is a generic procedure – you will need to write
your OWN procedure for your lab report – do NOT copy this one)
Safety precautions: You will be working with heat and glassware in this
lab. Therefore, you will be expected to wear safety goggles at ALL times in
the lab. In addition you will need long pants and closed shoes. Be careful
when handling the glass test tubes, and be careful when using the hot plates
(don’t change the heat settings at any point during the lab)
You will be working with your lab table to complete this experiment. Each lab table
will have the same setup, but will be placing liver pieces into water baths of
different temperature.
READ THE REMAINDER OF THIS PAGE AND FINISH WRITING THE
PROCEDURE ON PAGE 3.
Read the thermometer and record the temperature of your water bath. Do NOT
adjust the settings of the hot plate (if you have one). Then use the spoon to
transfer all 5 pieces of the raw liver into the water bath. Allow your pieces of
liver to sit in each environment for 5 minutes. In the meantime, clean your spoon in
the soap bath in order to prevent contamination later. When the 5 minutes have
passed, you are ready to test for the activity of the catalase enzyme in the liver.
You want to test the liver at the temperature of the water bath, so work quickly
and with one piece at a time (leave the other pieces in the water bath). Use your
spoon to remove one piece of liver and place it in a test tube. Make sure that the
piece of liver reaches the bottom of the test tube (not clinging to the side). Add
10 drops of hydrogen peroxide (labeled H2O2) to the test tube. Use a marker to
mark the highest point of rising bubbles in the test tube. Repeat this for the four
other pieces of liver in separate test tubes. Then use a ruler to measure the
heights of each test tube in millimeters.
Clean-up:
After completing all experiments, dispose of all test tube contents
into the large waste container. Clean out the test tubes in the wash bins and invert
the test tubes on your test tube rack to let them dry.
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Name____________________________________________Period_______ENTRY #________
PROCUDURE IS TO BE WRITTEN THE
NIGHT BEFORE THE LAB!!!!
Procedure used during the lab:
Use the 1st three steps and
finish writing the procedure using the information of the previous page.
1. Gather all materials together.
2. Set up 7 stations with water baths so that the effect of temperature
change on enzymes can be observed.
3. Put on __________________________.
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Name____________________________________________Period_______ENTRY #________
Data collection:
Record the Temperature__________
Small group data (each table):
Trials
1
2
3
4
5
Average (= sum of trials / 5)
Catalase activity (mm of bubbles)
Class Data Table (Use this table in Lab Report):
Title:_________________________________
IV and DV Included
Stations
Temperature of water bath
Catalase activity
(°C) IV
(averaged mm of bubbles from 5
List Highest to Lowest
individual trials) DV
Hot Plate
Hot Plate
Hot Plate
Hot Plate
Room
Temperature
Refrigerated
Ice Water
Narrative:
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Name____________________________________________Period_______ENTRY #________
Graph: TO BE COMPLETED AS HOMEWORK PRIOR TO
WRITE UP OF LAB REPORT
Create a graph using the results from the different temperatures. Label your
graph appropriately, and draw a trend that best represents your data.
Title:
___________________________
IV and DV Included
Y-axis label
DV
________________
X axis label IV:
_______________________
Narrative:
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Name____________________________________________Period_______ENTRY #________
Materials List
1. Hot plates
2. Ring stands
3. Celcius Thermometers
4. Large beakers 1000ml
5. Test tubes
6. Spoon
7. Marker
8. Pipette-the dropper for the hydrogen peroxide
9. Forceps- tweezers
10.
Test tube brushes
11.
Beef liver
12.
Glass rods
13.
Hydrogen peroxide
14.
Pans for washing and rinsing
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Name____________________________________________Period_______ENTRY #________
Liver Enzyme Lab Rubric
Introductory Components
Include Title that includes IV and DV
Include Purpose that summarizes lab
Include Hypothesis that can be tested by lab’s data
Each lab section has a heading and is underlined
Background Information
Identify the biomolecule in the liver that was tested
Identify purpose of enzymes correctly See page 66 in textbook
Discuss lock-and-key model correctly See page 66 in textbook
Identify method for measuring enzyme activity
Identify and describe your station in words or a picture with
labels (See materials list in packet)
Total: 10
2
3
3
2
Total: 27
6
6
6
4
5
Procedure
Summarize the steps of the procedure accurately
Use a numbered list of steps
6
2
Data
Include Class Data Table labeled Figure 1
Include correct type of Graph labeled Figure 2
Include title for data table AND graph (with IV/DV)
Include Narrative for both data table and graph, Figures 1 and 2
Label the X axis with title and units
Label the Y axis with title and units
Show an even scale for X and Y axis
Plot data correctly AND show line of best fit
IV and DV on correct axes in graph
3
3
3
2
2
2
3
4
3
Conclusion
Restate the purpose
State major findings (Example: identify temp of highest enzyme
activity, temp of denaturing and other important points)
Restate the hypothesis by quoting, was it supported or not
supported and explain why
Suggest specific improvement to lab procedure (do not use
more trials or more liver)
No personal pronouns in lab report
Total Points Possible 100
Total: 8
Total: 25
Total: 30
5
7
7
7
4
Total Points Earned________________
7