Lab Bench Activity ​Enzyme Catalysis
Name:
​http://www.phschool.com/science/biology_place/labbench/lab2/active.html
Enzyme Structure
Active site:
Picture of enzyme with substrate and active site:
Binding Specificity
When will a substrate bind to the active site?
Induced Fit
Induced fit:
Draw what is happening when an induced fit takes place:
Some Factors that Affect Enzyme Action
1.
2.
What happens to the enzyme after it is altered/
pH and Enzyme Function
Pepsin works best under_________ conditions.
Lipase works best under _________ conditions.
What happens to catalysis when an enzyme is subjected to a pH far from its optimum range?
Temperature and Enzyme Function
As temperature increases, the rate of reaction _______________
Boiling temperatures will ___________ enzymes.
Experiment
Click through the experiment.
Analysis of Results
We can calculate the rate of a reaction by measuring, over time, either the disappearance of
substrate (as in our catalase example) or the appearance of product (as in the above graph). For
example, on the graph above, what is the rate, in moles/second, over the interval from 0 to 10
seconds?
Calculate the rate in moles/second between 40 and 50 seconds
1. During what time interval is the enzyme working at its maximum velocity?
a. 0–30 seconds
b. 60–120 seconds
c. 120–180 seconds
d. Over the entire time course
2. In order to keep the rate constant over the entire time course, which of the following should be
done?
a. Add more enzyme.
b. Gradually increase the temperature after 60 seconds.
c. Add more substrate.
d. Add H​2​SO​4​ after 60 seconds.
3.Which of the following graphs represents the rate of the reaction shown above? Notice that in the
graphs below, the y-axis is number of molecules/sec.
a.
b.
c.
d.
4. What is the role of sulfuric acid (H​2​SO​4)​ in this experiment?
a. It is the substrate on which catalase acts.
b. It binds with the remaining hydrogen peroxide during titration.
c. It accelerates the reaction between enzyme and substrate.
d. It blocks the active site of the enzyme.
e. It denatures the enzyme by altering the active site.
5. A student was performing a titration for this laboratory, and accidentally exceeded the endpoint.
What would be the best step to obtain good data for this point?
a. Estimate the amount of KMnO​4​ that was in excess, and subtract this from the result.
b. Repeat the titration using the reserved remaining sample.
c. Obtain data for this point from another lab group.
d. Prepare a graph of the data without this point, and then read the estimated value from the
graph.