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(Solved) Observing the Effects of Concentration on Enzyme Activity Background information: Enzymes are proteins that speed up the rate of a chemical reaction...

Research the role of hydrogen peroxide in terms of its importance to proper cell function and as that of a toxin. Research catalase and its importance in preventing peroxide toxicity. Include the chemical reaction of the metabolism of peroxide by catalase. 

From your research and the reading of the lab procedure construct a hypothesis. State the IV and DV, constants and control of the experiment. 

Observing the Effects of Concentration on Enzyme Activity
Background information:
Enzymes are proteins that speed up the rate of a chemical reaction that would
otherwise happen more slowly. The enzyme may be altered, but not consumed
by the completed reaction. There are hundreds of different enzymes in each
human cell. Each enzyme is responsible for one particular chemical reaction that
occurs in the cell.
Hydrogen peroxide is a chemical used to treat wounds. It is an effective antiseptic
because it is deadly to cells. Of course, the cells intended for destruction are
bacterial cells that may enter an open wound, not your own cells.
It may be surprising to find out that hydrogen peroxide is produced by the body
for such purposes as fighting infection but if allowed to build up in cells may also
become toxic. The enzyme catalase, which is found in the cells of many living
things, speeds up the reaction that breaks down hydrogen peroxide into nontoxic
This lab will utilize a procedure that could be used to test enzyme activity in
various body tissues. The simple test measures the effect of enzyme
concentration on reaction rate, the speed of the chemical reaction. Disks of filter
paper will be soaked in different concentrations of the enzyme catalase and the
rate of the breakdown of hydrogen peroxide will be measured.
Pre-lab: The following research will serve as the “Introduction”.
Research the role of hydrogen peroxide in terms of its importance to proper cell
function and as that of a toxin. Research catalase and its importance in
preventing peroxide toxicity. Include the chemical reaction of the metabolism of
peroxide by catalase.
From your research and the reading of the lab procedure construct a hypothesis.
State the IV and DV, constants and control of the experiment. Formal Lab Write-up Change/Clarification:
The introduction may not exceed 1 page, must include at least two paragraphs,
reference sources by using parenthetical (in-text) citations and works cited page in
APA format and use at least 3 sources. Wikipedia may not be used as a source!
Your lab report should have the following sections:
Title page
Introduction (includes your hypothesis, null hypothesis, identification of IV, DV,
constants and control)
Results and Analysis (see questions at end of lab for guidance)
Works cited (APA format; use parenthetical citation in the paper)
Materials: safety goggles
medicine cups for dilutions (6)
marking pencils
100% catalase (stock) solution
10 ml graduated cylinder
stirring rod
test-tubes dilute hydrogen peroxide solution
filter paper disks (18)
paper towels
watch or clock with second hand
metric ruler Procedure:
1. Put on safety goggles.
2. Determine how you will make a series of dilutions of the enzyme catalase. One way to
make a dilution is to start out with a 100% enzyme solution. To make 10 mL of a 50%
enzyme solution, for example, mix 5 mL of water and 5 mL of the 100% enzyme solution.
Complete the following table to determine how you will mix each of the enzyme dilutions
needed in this lab. Note: The first two lines are completed.
Enzyme Dilutions
Final quantity
needed Concentration
of final solution mL of catalase mL of water 10 mL 100% 10 0 10 mL 80% 8 2 10 mL 60% 10 mL 40% 10 mL 20% 10 mL 0% 3. Use a marking pencil to label six medicine cups for the enzyme solutions as follows: 100%,
80%, 60%, 40%, 20%, and 0%.
4. Obtain a cup containing 30 mL of the 100% enzyme solution.
5. Use a graduated cylinder to measure 10mL of the 100% enzyme solution in to the medicine
cup labeled 100%.
6. Prepare and label 10 mL of each of the dilutions according to the measurements in the
enzyme dilution table on the previous page. Mix each dilution thoroughly with a stirring
rod. Note: Be sure to rinse the stirring rod with tap water after making each dilution.
7. Fill the test tube with 20 mL of hydrogen peroxide solution. Note: If you are measuring the
hydrogen peroxide solution in a graduated cylinder, clean the cylinder very carefully when
finished. You do not want to mix catalase and hydrogen peroxide in the cylinder. 8. Use forceps to pick one of the filter-paper disks. Hold the forceps as close to the edge of
the disk as possible. Submerge the disk in 100% catalase solution for five seconds.
Continue to hold the disk with the forceps.
9. Remove the disk from the solution, and blot it dry on the paper towel for five seconds.
10.Drop the disk into the hydrogen peroxide. Measure the time it takes for the disk to rise to
the surface of the hydrogen peroxide. Begin timing as soon as the disk touches the surface
of the hydrogen peroxide. Use the metric ruler to measure the distance the disk sinks in
the hydrogen peroxide. Multiply this measurement by two to determine the distance
traveled. Enter the time and the distance traveled in the column for Trial 1 in the data table
Reaction Rate of Enzyme Dilutions
Catalase Time in seconds (s)
1 Trial
2 Trial
3 Avg. Distance in millimeters
Trial Trial Trial Avg. (mm/s)
3 100
11.Repeat steps 8 through 10 two more times, using a clean filter –paper disk each time. Enter
the times and distances traveled in the columns for Trial 2 and Trial 3. Find the average
time and average distance traveled. Then calculate the reaction rate by dividing the
average distance by the average time.
Reaction rate = average distance
average time
12.Repeat steps 8 through 11 for the 80%, 60%, 40% and 20% solutions. Complete the data
table on the previous page for each trial for each solution. Note: Be sure to use a clean
filter-paper disk and a clean paper towel for each trial to avoid contamination.
13.Repeat steps 8 through 11 for the 0% solution. Note: If the disk has not risen to the surface
within three minutes, write “no reaction” in the data table. 14.Dispose of solutions in the sink.
15.Clean up the lab area and wash your hands before leaving the class.
16. Submit your group’s data to Schoology. When the class data is distributed, download a
copy. In Excel, plot a line graph of the reaction rates of the enzyme dilutions for the class data.
Results/ Analysis
5. As proteins, enzymes contain peptide bonds. Describe a peptide bond.
What type of chemical reaction creates peptide bonds between amino acids?
Which concentration of catalase had the fastest reaction time, the slowest reaction time?
Why did you measure the distance traveled by the disks to determine reaction rate?
Based on the graph and the overall slope of the line, what can you conclude about the
effect of enzyme concentration on reaction rate?
6. Is the procedure a good way to test enzyme activity? Explain your answer.
7. In the lab, the term 100% enzyme is only relative – it is merely the concentration of the
enzyme the teacher mixed. In other words, the enzyme concentration could have been
much higher. Do you think that the trend noted in the graph above would continue if the
enzyme samples were even more concentrated than those in the lab? Explain your answer.


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