LESSON PLAN
Topic: Enzymes
Name: Afrodita Fuentes
Class: Biology
Grade Level: High School
A. Major Concepts:
 enzymes are proteins that catalyze chemical reactions without altering the reaction
equilibrium
 enzyme activity depends on the temperature, ionic conditions, and pH of the surroundings
B. Performance Objective / Content Standards:
 Students will be able to … when the lesson is complete
 describe the process of a chemical reaction
 explain how enzymes catalyze chemical reactions without altering the reaction
equilibrium
 Identify the factors that affect enzyme action
 recognize optimum conditions (temperature, pH, enzyme and substrate
concentrations) for enzyme activity by observing and analyzing graphs
 Write 1-3 concluding paragraphs about enzymes
 Levels of Reasoning Developed or used: knowledge, comprehension, application,
analysis, synthesis
 California State Science Content Standards: Biology/Life Science - b. Students know
enzymes are proteins that catalyze biochemical reactions without altering the reaction
equilibrium and the activities of enzymes depend on the temperature, ionic conditions, and
the pH of the
 Cognitive Goals for Students:
 Planning
 Hypothesizing
 Timing
 Creating graphs
 Observing & collecting data
 Analyzing data
C.




Materials and Equipment for enzyme lab (group):
Test tube holder  6 Test tubes & 1 test tube rack
Thermometer
 10-ml Graduated cylinder
Stirring rod
 Straight-edged razor blade
pH paper
 3 beakers for water baths
 Scissors and Forcep




1molar HCl solution (in dropper bottle)
1molar NaOH solution (in dropper bottle)
10 ml 3% Hydrogen peroxide solution
Fresh raw liver & chicken, Apple, and
Potato
Notes:
1 pound of liver is enough for 5 classes (30 groups) & ¼ lb of chicken is enough. Liver is
available at any supermarket.
For temperature effect on catalase, works best if the liver is cooked by the teacher first
D. Independent practice / Assignments:
 Questions & summary of enzyme notes
 Enzyme book questions
 Enzyme worksheet problems
 Brainstorming & writing
E. Outline of Lesson:
Activity
Day 1 Warm-up
Introduction
Lecture/Discussion
Activities
Homework
Day 2
Warm-up
Introduction
Lecture/Discussion
Activities
Homework
Warm-up
Introduction
Lecture/Discussion
Activities
Homework
Day 4 Warm-up
Introduction
Activities
*handouts included
Day 3
Cues:
Content
Enzyme section outline
Protein questions & crackers activity
Enzyme – Cornell note & discussion*
Video - egg protein structure change with heat
Begin key terms definitions & drawings
Breakdown of glucose in saltine crackers by
amylase in saliva
Key term definitions & pictures
Questions & summary of notes
Enzyme Catalase readings
Objectives
Pre-Lab questions*
Enzyme Lab Part I: Normal Catalase activity*
Enzyme book questions*
Enzyme worksheet
Objectives & hypothesis
Lab set-up & instructions
Time (min)
5 min
15 min
25 min
10 min
Enzyme Lab: Part II & III*
Lab questions*
Enzyme concept map*
Next topic
Enzyme lab: conclusion write-up
40 min
10 min
10 min
30 min
5 min
10 min
10 min
20 min
ENZYMES – note
Enzymes - are proteins made of amino acids
- are catalysts b/c they speed up chemical reactions & lower the activation
energy
- are reusable b/c they remain unchanged after the reaction
- are specific b/c there is a perfect enzyme for a certain substrate
Questions:
-
have a 3D shape which can be destroyed/denatured w/extreme changes
in pH & temperature
have active sites = places where substrate (food & waste) molecules
attach
Draw the enzyme with an active site + a substrate:
Ex) Catalase  breaks down hydrogen peroxide (waste produced in
cells) into
2H2O2 ----> 2H2O + O2
Lactase  breaks down lactose in milk
Protease  breaks down proteins
Lipase  breaks down lipids
How Enzymes Work?
 Active sites on enzymes = places to which a specific substrate binds
 Enzyme-substrate complexes form (when substrates attach to active
sites on the enzymes) to break apart or put together substances at a
fast rate
E+ S 
ES

E + P
There are two models of enzyme action
1. lock & key model  substrate & the enzyme fit together perfectly
2. induced-fit model enzymes change shape slightly to accommodate the
substrate
Draw figure 4-15
Factors affecting enzyme action
1. Temperature – enzymes work best at certain temperatures, – 37oC is
best for human enzymes in the body
2. pH – enzymes work best at certain pH; basic, neutral, and/or acidic
environments
ex.) Amylase in saliva at pH 7, Pepsin in the stomach at pH 2-3, &
Trypsin in the intestines at pH 9
3. Substrate & enzyme concentrations – how fast reactions take place
depends on how much of the substrate & enzyme is available.
4. Coenzymes – helpers such as vitamins & minerals
Summary
ENZYMES – book questions
Read pages 68-71 to answer the following questions in complete sentences. Do not copy
exactly from the book, paraphrase. Use diagrams, pictures, graphs, etc to show your
understanding.
1. What are enzymes?
2. Are enzymes proteins?
3. What are coenzymes?
4. What are the functions of enzymes?
5. What are the elements found in enzymes?
6. What is a catalyst?
7. What enzyme breaks-down proteins?
8. Compare and contrast the two models of enzyme action.
9. Draw figure 4-15 and copy its caption.
10. What are the factors that affect how enzymes work?
11. Classify the following substances as carbohydrate, lipid, protein, or nucleic acid: maltose,
chlorophyll, DNA, vegetable oil, fructose, RNA, wax, glycogen, insulin, and albumin.
 Activities: warm-ups, note, demo, videos, book questions, lab, discussions
1. Observing the Activity of Enzyme CATALASE – Lab in groups
a. Pre-Lab questions
b. normal Catalase activity: occurrence of Catalase & Catalase is reusable
c. Effect of Temperature of Catalase activity: hypothesis, observations, questions
d. Effect of pH on Catalase Activity: hypothesis, observations, questions
e. Post-Lab questions
f. Conclusions
Observing the enzyme CATALASE (Original copy from internet
– see my modified version following this one)
INTRODUCTION: what would happen to your cells if they made a
poisonous chemical? You might think that they would die. In fact, your cells
are always making poisonous chemicals. They do not die because your cells
use enzymes to break down these poisonous chemicals into harmless
substances. Enzymes are proteins that speed up the rate of reactions that
would otherwise happen more slowly. The enzyme is not altered by the reaction. You have
hundreds of different enzymes in each of your cells. Each of these enzymes is responsible
for one particular reaction that occurs in the cell.
In this lab, you will study an enzyme that is found in the cells of many living tissues. The
name of the enzyme is catalase (KAT-uh-LAYSS); it speeds up a reaction which breaks
down hydrogen peroxide, a toxic chemical, into 2 harmless substances--water and oxygen.
The reaction is as follows:
2H2O2 ----> 2H2O + O2
This reaction is important to cells because hydrogen peroxide (H2O2) is produced as a
byproduct of many normal cellular reactions. If the cells did not break down the hydrogen
peroxide, they would be poisoned and die.
PRELAB REVIEW:
Before you begin this lab, review pH. Recall that pH is the measure of the acidity or
alkalinity of a solution. An acidic solution has many hydrogen ions (H+) and a pH below 7. An
alkaline, or basic, solution has very few hydrogen ions and a pH above 7. A neutral solution has a
pH of 7.
Recall that the substrate is the molecule that the enzyme acts on, and the products are the
molecules produced by the reaction. Review why enzymes are reusable. Under certain conditions
enzymes are denatured. An enzyme is denatured when the protein molecule loses its proper shape
and cannot function. Some things that can denature an enzyme are high temperatures, extremes of
pH, heavy metals, and alcohol.
PRE-LAB PREP:
Mix 1 molar concentration solutions of hydrochloric acid and sodium hydroxide. For the
HCl, mix 2.2 ml of concentrated acid with enough distilled water to make a total volume of 25 ml.
(REMEMBER: NEVER ADD WATER TO ACID, ALWAYS ADD ACID TO WATER). For
the sodium hydroxide, add 1.0 g of NaOH to enough distilled water to make a total volume of 25
ml. 3% Hydrogen peroxide is what you buy in the grocery store.
MATERIALS:
6 Test tubes and rack
Test tube holder
Thermometer
Stirring rod
pH paper
10-ml Graduated cylinder
Straight-edged razor blade
3 beakers for water baths
Scissors and Forceps
(tweezers)
1molar HCl solution (in dropper bottle)
1molar NaOH solution (in dropper
bottle)
40 ml 3% Hydrogen peroxide solution
Fresh liver, chicken meat, Apple, and
Potato
PROCEDURES AND ANALYSIS QUESTIONS
Part I – PROCEDURE -- Normal Catalase Activity
NOTE: Be sure to clean your stirring rod (and test tubes) between steps.
1. Place 2 ml of the 3% hydrogen peroxide solution into a clean test tube
2. Add a small piece of liver to one test tube. Observe the bubbles; what gas is being
released?
Throughout this investigation you will estimate the rate of the reaction (how rapidly the
solution bubbles) on a scale of 0-5 (0=no reaction, 1=slow,...., 5= very fast). Assume
that the reaction in step 2 proceeded at a rate of "4" and record the speed in DATA
TABLE 1, and DATA TABLE 2 as the rate at room temperature.
3. Recall that a reaction that absorbs heat is endothermic; a reaction that gives off heat is
exothermic. Now, feel the temperature of the test tube with your hand.
Has it gotten warmer or colder? Is the reaction endothermic or exothermic?
Is Catalase Reusable?
4. Pour off the liquid into a second clean test tube. 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? Why?
5. Add another 2 ml of hydrogen peroxide to the liver remaining in the first test tube.
Can you observe a reaction? What do you think would happen if you poured off this
liquid and added more hydrogen peroxide to the remaining liver?
Are enzymes reusable?
Occurrence of Catalase
Catalase is present in many kinds of living tissues. You will now test for the presence of
catalase in tissues other than liver.
6. Place 2 ml of hydrogen peroxide in each of 3 clean test tubes. To the first tube, add a
small piece of potato. To the second tube, add a small piece of chicken. To the last tube,
add a small piece of apple. As you add each test substance, record the reaction rate (0-5)
for each tube in TABLE 1.
Which tissues contained catalase?
Part II – PROCEDURE -- Effect of Temperature on Catalase Activity
7. Put a piece of liver into the bottom of a clean test tube and cover it with a small amount
of distilled water. Place this test tube in a boiling water bath for 5 minutes. What will
boiling do to an enzyme?
8. Remove the test tube from the hot water bath, allow it to air cool, then pour out the water.
Add 2 ml of hydrogen peroxide. CAUTION: Use a test-tube holder when handling the
hot test tubes. What is happening in the test tube? Record the reaction rate (0-5) in
DATA TABLE 2.
9. Put equal quantities of liver into 2 clean test tubes and 1 ml H2O2 into 2 other test tubes.
Put one test tube of liver and one of H2O2 into each of the following water baths: Ice
bath (0 deg.C) and Warm water bath (37 deg.C)
10. After 3 minutes, pour each tube of H2O2 into the corresponding tube of liver and
observe the reaction. Record the reaction rates (0-5) in DATA TABLE 2. You recorded
the reaction rate for room temperature earlier.
What is the "optimum" temperature for catalase? (This is the temperature at which the
reaction proceeds fastest.)
Why did the reaction proceed slowly at 0 deg.C?
Why did the reaction not proceed at all at 100 deg.C?
Part III – PROCEDURE -- Effect of pH on Catalase Activity
12. Add 2 ml hydrogen peroxide to each of 3 clean test tubes. Treat each tube as follows:
Tube 1--add a drop of 1molar HCl (acid) at a time until pH 3.
Tube 2--add a drop of 1molar NaOH (base) at a time until pH 10.
Tube 3--adjust the pH to 7 by adding single drops of either 1molar HCl or 1molar NaOH
as needed.
CAUTION: Do not let acids or bases contact your skin or clothing. Swirl each test tube
after adding each drop and measure the pH of each solution with pH paper. To do this,
remove a drop or two of solution from a test tube using a clean glass stirring rod. Rinse
your stirring rod and wipe dry before you dip it into each test tube. Place the drop on pH
paper. Record the pH of each solution in DATA TABLE 3.
13. Next, add a small piece of liver to each test tube. Estimate the reaction rates (0-5) and
record in DATA TABLE 3.
14. Does there appear to be a pH "optimum"? At what pH?
What is the effect of low or high pH on enzyme activity?
TABLE 1: Occurrence of Catalase
Sample
Rate of Enzyme Activity
Liver
Potato
Chicken
Apple
TABLE 2: Temperature effect on Liver Catalase Activity
Temperature
Rate of Enzyme Activity
___ oC Freezing Temp.
___ oC Room Temp.
___ oC Body Temp.
___ oC Boiling Temp.
TABLE 3: pH effect on Catalase Liver Activity
pH
Rate of Enzyme Activity
3
7
10
Understanding the enzyme CATALASE – Lab #
Good for ESL level - 150 PTS
Observing the enzyme CATALASE – read & underline or highlight (10 pts)
INTRODUCTION: what would happen to your cells if they made a poisonous chemical? You might think
that they would die. In fact, your cells are always making poisonous chemicals. They do
not die because your cells use enzymes to break down these poisonous chemicals into
harmless substances. Enzymes are proteins that speed up the rate of reactions that would
otherwise happen more slowly. The enzyme is not altered by the reaction. You have
hundreds of different enzymes in each of your cells. Each of these enzymes is responsible
for one particular reaction that occurs in the cell.
In this lab, you will study an enzyme that is found in the cells of many living tissues. The name
of the enzyme is catalase (KAT-uh-LAYSS); it speeds up a reaction which breaks down hydrogen peroxide, a
toxic chemical, into 2 harmless substances--water and oxygen. The reaction is as follows:
2H2O2 ----> 2H2O + O2
This reaction is important to cells because hydrogen peroxide (H2O2) is produced as a byproduct of many
normal cellular reactions. If the cells did not break down the hydrogen peroxide, they would be poisoned and
die.
PRELAB REVIEW:
Before you begin this lab, review pH. Recall that pH is the measure of the acidity or alkalinity of a
solution. An acidic solution has many hydrogen ions (H+) and a pH below 7. An alkaline, or basic, solution
has very few hydrogen ions and a pH above 7. A neutral solution has a pH of 7.
Recall that the substrate is the molecule that the enzyme acts on, and the products are the molecules
produced by the reaction. Review why enzymes are reusable. Under certain conditions enzymes are
denatured. An enzyme is denatured when the protein molecule loses its proper shape and cannot function.
Some things that can denature an enzyme are high temperatures, extremes of pH, heavy metals, and alcohol.
Objectives:
1. identify tissues that have the enzyme catalase
2. study the enzyme catalase activity
3. explore factors that affect enzyme action (pH, Temperature, etc.)
4. understand that enzymes are specific and reusable
Pre-Lab Questions (20 pts)
1. The reaction is
2. Why is this reaction necessary in the body?
3. The enzyme is ________________ & the substrate is ___________________ (H2O2).
4. The reactants are _______________________ & the products are ________________
5. Protein Denaturation is ____________________________________________.
6. Denaturation is caused by ________________________________________________.
7. Independent variables: ___________________________________________________
8. Dependent variables: _____________________________________________________
Part I - Normal Catalase Activity
DATA


2 points/question
10 points/chart with
description & color
Occurrence of Catalase
1. Catalase is present in many kinds of living tissues. You will test for the presence of catalase in
tissues other than liver.
2. Place 2 ml of hydrogen peroxide in each of 3 clean test tubes. To the first tube, add a small piece of
potato. To the second tube, add a small piece of chicken. To the last tube, add a small piece of apple.
As you add each test substance, record the reaction rate (0-5) for each tube in TABLE 1.
Which tissues contained catalase? ____________________________________________.
TABLE 1: Occurrence of Catalase (could be done as a class to establish the liver is the best source of catalase)
2 mL H2O2 +
2 mL H2O2 +
2 mL H2O2 +
2 mL H2O2 +
Liver catalase
Chicken catalase
Apple catalase
Potato catalase
Description:
Description:
Description:
Description:
Rate of reaction __
Rate of reaction __
Rate of reaction __
Rate of reaction __
Throughout this investigation you will estimate the rate of the reaction (how rapidly the solution bubbles)
on a scale of 0-5 (0=no reaction, 1=slow to5= very fast).
Is Catalase Reusable?
3. Place 2 ml of the 3% hydrogen peroxide solution into a clean test tube
4. Add a small piece of liver to one test tube. Observe the bubbles; what gas is being released?
_________
5. Recall that a reaction that absorbs heat is endothermic; a reaction that gives off heat is exothermic.
Now, feel the temperature of the test tube with your hand.
6. Has it gotten warmer or colder? Is the reaction endothermic or exothermic? __________________
Is Catalase Reusable? ________________________
7. Pour off the liquid into a second clean test tube. 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? ________________________Why? ________________________________
8. Add another 2 ml of hydrogen peroxide to the liver remaining in the first test tube. Can you observe
a reaction? ____________ What do you think would happen if you poured off this liquid and added
more hydrogen peroxide to the remaining liver? ______________________________
Are enzymes reusable? _______________.
TABLE 2: Is Catalase Reusable? (could be done as a class)
2 mL H2O2 + liver
Description:
Liquid + new liver
Reaction rate __ Why?
Reaction rate __
Description:
Description:
New H2O2 + old liver
Reaction rate __ Why?
Description:
Part II – Effect of Temperature on Catalase Activity (could be done by add group numbers & then
share data with even group numbers)
PROCEDURE
9. Put a piece of boiled liver into the bottom of a clean test tube and cover it with a small amount of
distilled water. What will boiling do to an enzyme? ___________________________________.
10. Add 2 ml of hydrogen peroxide to the boiled liver. What is happening in the test tube?
_____________ _______________________ Record the reaction rate (0-5) in DATA TABLE 2.
11. Put equal quantities of liver into 2 clean test tubes and 1 ml H2O2 into 2 other test tubes. Put one test
tube of liver and one of H2O2 into each of the following water baths: Ice bath (0 deg.C) and Warm
water bath (37 deg.C)
12. After 3 minutes, pour each tube of H2O2 into the corresponding tube of liver and observe the
reaction. Record the reaction rates (0-5) in DATA TABLE 2. You recorded the reaction rate for
room temperature earlier.
What is the "optimum" temperature for catalase? (This is the temperature at which the reaction
proceeds fastest.) ________________________________
Why did the reaction proceed slowly at 0 deg.C? _______________________
Table 3: Effect of Temperature on Catalase
2 mL H2O2 + boiled Liver 2 mL H2O2 + liver catalase
catalase (___oC)
In warm water bath (__ oC)
Rate of reaction __
Description:
Rate of reaction __
Description:
2 mL H2O2 + liver catalase
In iced water bath (__ oC)
Rate of reaction __
Description:
Part III – Effect of pH on Catalase Activity (could be done by even group numbers & then share data
with odd group numbers)
PROCEDURE
12. Add 2 ml hydrogen peroxide to each of 3 clean test tubes. Treat each tube as follows:
Tube 1--add a drop of 1molar HCl (acid) at a time until pH 3.
Tube 2--add a drop of 1molar NaOH (base) at a time until pH 10.
Tube 3--adjust the pH to 7 by adding single drops of either 1molar HCl or 1molar NaOH as
needed.
CAUTION: Do not let acids or bases contact your skin or clothing. Swirl each test tube after
adding each drop and measure the pH of each solution with pH paper. To do this, remove a drop
or two of solution from a test tube using a clean glass stirring rod. Rinse your stirring rod and
wipe dry before you dip it into each test tube. Place the drop on pH paper. Record the pH of each
solution in DATA TABLE 4.
15. Next, add a small piece of liver to each test tube. Estimate the reaction rates (0-5) and record in
DATA TABLE 4.
16. Does there appear to be a pH "optimum"? __________ At what pH? _____________
What is the effect of low or high pH on enzyme activity? __________________________.
Table 4: Effect of pH on Catalase Activity
3 mL H2O2 + boiled Liver catalase
3 mL H2O2 + liver
catalase
At pH 3 (HCl)
At pH 7 (H2O)
Rate of reaction __
Rate of reaction __
Description:
Description:
3 mL H2O2 + liver
catalase
At pH 10 (NaOH)
Rate of reaction __
Description:
Write one page (2-3 paragraphs) summarizing what you learned about enzymes. What are they?
What is their structure like? What do they do? What affects the way they work? Anything
special… 20 pts
 Summary
Enzyme Warm-up #
Construct a concept map with the following words: catalyst,
protein, substrate, enzyme, active site, temperature, pH,
substrate & enzyme concentration, cofactors, lock-key model,
induced-fit model, etc.
Write 1-3 paragraphs about enzymes
F. Homework:
 Handouts of problem sets: Enzyme activity graphs
 Readings: Chapter 4 pages 68-71, lab intro, enzymes used at home
G. References:
 Textbook – Biology the study of life: Chapter 4 pages 68-71
 http://plantphys.info/Plant_Physiology/enzymefactors.html - enzyme graphs
 http://www.sumanasinc.com/webcontent/anisamples/nonmajorsbiology/proteinstructure.h
tml - egg protein structure change with heat
 Transparencies from textbook ancillary materials