What are the effects of pH on enzyme activity?
Hypothesis: Make a hypothesis as to placing an enzyme in acidic environment will change the rate of an enzyme controlled reaction
If __________________________________________, then ______________________________________________.
Background information
Potato and other living tissues contain the enzyme
catalase.
This enzyme breaks down
hydrogen peroxide, which is a harmful by-product of the process of
cellular
respiration if it builds up in concentration in the cells.
If we use
potato or other tissue containing this enzyme, we can use this to
measure the
relative influence of varying several different factors on the activity
of
enzymes in living tissue.
Materials: (per student group)
100 ml or other graduated cylinder, 2 test
tubes,
15 ml of 1% H2O2,
vinegar as an acidic solution, water,
test tube rack, potato, and labeling pencil
Procedure:
1. Place one or two 1 cm3 chunks of potato in the bottom
of two
different test tubes.
2. Place 5 ml of an acid solution on the potato in the first test tube which you will
label acid and 5 ml of water on
the potato in the second test tube you will label
water.
3. Add 5-7 ml of hydrogen peroxide to the solution in each tube and record the
relative amount of bubbling you see in each.
Results:
Enzyme Activity at Different pH Levels
| Test Tube pH Level | Relative Amount of Bubbling (Reaction) |
. Conclusion: (include the following in your conclusion in composition style)
1. Did your results support your hypothesis? Explain
2. Explain why you believe you observed the results you observed.
Terms such as optimum conditions and denature should
be included in your explanation.
3. In class we learned that most enzymes in living systems function optimally
at a pH of 7.0.
Did the results of our lab support these observations? Explain why
or why not completely.
4. List and explain at least two possible sources of error in this lab
activity.
5. Identify the control, independent variable, and dependent variable in this
investigation and explain why you identified each as this.
Supplemental Activity
Your instructor believes that enzyme controlled reactions will not
function well
in strong saline (salt) solutions. Design a lab
routine using
the materials of this lab to test this hypothesis. Please
include
the problem to be tested, your instructor's hypothesis, a list of
materials, and
most importantly a procedure to test this. Identify
the
control, independent variable, and dependent variable in this
procedure.