MERAMER BIO 141 Effect of P H Enzyme Lab Questions
1. In this activity, you will study the effect of pH, temperature, and lactose concentration on
lactase activity. By the end of this activity, you should be able to:
a. design experiments to study the effects of pH, temperature, and substrate
concentration on enzyme activity.
b. analyze data related to enzyme activity.
c. identify the components of the scientific method.
d. identify components of the substrate-enzyme-product system being studied.
e. summarize and communicate your lab data.
• To prepare for the lab, watch the following video and think about enzymes, substrates,
products, maximum rate of reaction, and optimal conditions.
• To complete the lab activity, watch the Zoom link for lab posted on Canvas and go to the
following website (https://sites.google.com/site/biologydarkow/lactase-enzyme-simulation
• You do not submit this document on Canvas. This document includes the instructions you need
to complete the lab, but the data you submit is the completed Lactase Enzyme Data document
Experiment I: The effect of pH on lactase activity. Click on the Simulate tab. The standard condition
settings are: lactose for 500 mg/dL , pH at 7.0 and temperature at 250C, and 5 mmol lactase enzyme
solution. You will vary one of these conditions in each experiment. In this Experiment I, you are varying
pH. The condition you are varying is the independent variable for that experiment. The outcome you
measure for that experiment is the dependent variable. The dependent variable in Experiment I is
glucose produced and is a measure of the rate of the enzyme activity. The hypothesis of an experiment
is a tentative proposed relationship of the independent and dependent variable of the experiment. The
hypothesis of Experiment I is pH does not affect the amount of glucose produced in a reaction catalyzed
Experiment I has two parts: I. determining the inflection point and interval of interest and II.
determining the optimum pH for lactase activity.
I. Determining the inflection point and interval of interest. Before you can begin your
experiment, you must determine the interval of pH which will give you the most valuable,
relevant data. Start by running a simulation with the standard initial lactose, temperature
and lactase enzyme solution. Run simulations at a pH of 3. Record the glucose
concentration (mg/dL) at 4, 7 and 11 minutes. Repeat the simulations at a pH of 5, 7, 9, and
11. Record the glucose concentration (mg/dL) at 4, 7 and 11 minutes.