Download Enzyme Activity

ENZYME ACTIVITY
I. ARE ENZYMES SPECIFIC AND WHAT IS MEANT BY LOCK AND KEY
MECHANISM?
An enzyme and four different molecules are shown in the diagram below:
A. Can more than one molecule fit the enzyme? _________________________
B. Do you think the enzyme could be reused? _________________________
_____ 1. The enzyme would most likely affect reactions involving:
a. Molecule A, only
b. Molecule C, only
c. Molecules B and D
d. Molecules A and C
_____ 2. Based on your answer above, what would you say about enzymes?
a. Enzymes are very specific
b. Enzymes are nonspecific
c. A specific enzyme can regulate only one type of reaction
d. A specific enzyme can regulate several different types of reactions
e. Both a and c
Base your answers to questions 3 through 5 on the diagram below that represent a
human enzyme and four types of molecules present in solution in a flask.
_____ 3. Which molecule would most likely react with the enzyme? _____________________
4. Explain your answer to question 3
5. Why do you think that the specific action of an enzyme is often explained as a lock
& key mechanism (analogy)?
In this analogy, the lock is the enzyme and the key is the substrate. Only the
correctly sized key (substrate) fits into the keyhole (active site) of the lock
(enzyme).
Smaller keys, larger keys, or incorrectly positioned teeth on keys (incorrectly
shaped or sized substrate molecules) do not fit into the lock (enzyme). Only the
correctly shaped key opens a particular lock.
II. HOW DOES pH AFFECT ENZYME ACTION?
Base your answers to questions 6-13 on the graph below:
6. What pH does pepsin work best at? ________________________
7. Is the pH acid or basic? _________________________________
8. In what organ of the digestive system does pepsin work? ______________________
9. What pH does trypsin work best at? _______________________________
10. Is the pH acid or basic? _________________________________
11. In what organ of the digestive system does trypsin work _______________________
12. At what pH does neither enzyme work well? ___________________________________
13. What statement can you say about enzyme activity at a very low pH and a very
high pH? _________________________________________
III. HOW DOES TEMPERATURE AFFECT ENZYME ACTIVITY?
Base your answers to questions 14-18 on the graph below:
14. What temperature does the enzyme work best at? ____________________________
15. What happens to enzyme activity at 60 degrees Celsius? ______________________
16. What happens to enzyme activity at 0 degrees Celsius? ________________________
17. What can you say about the affect of temperature on enzyme activity? ___________
18. Some snake venoms are harmful because they contain enzymes that destroy
blood cells or tissues. The damage caused by snakebite could best be slowed by:
a. Applying ice to the bite area.
b. Drinking large amounts of water.
c. Inducing vomiting
d. Increasing blood flow to the area.
IV. HOW DOES ENZYME CONCENTRATION & SUBSTRATE CONCENTRATION
EFFECT ENZYME ACTIVITY?
Using the graphs below explain the effects of substrate concentration and enzyme
(catalyst) concentration on enzyme activity. Be sure to explain the reason for this
effect.
HOW WELL DID YOU UNDERSTAND THIS EXERCISE?
19. What kind of organic molecule is an enzyme?
20. List 2 internal environmental factors that affect how well enzymes function.
21. What happens to water when you heat it to 100°C?
22. What happens to proteins dissolved in that water when you heat it to 100°C?
23. What specific change happens to an enzyme that stops it from working when
you heat it?
24. Explain why changing the shape of an enzyme could affect the ability of the
enzyme to function.
25. What most likely happens to the rate of reaction of a human enzyme when the
temperature is increased gradually from 10°C to 30°C. Explain your answer.
26. What most likely happens to the rate of reaction of a human enzyme when the
temperature is increased gradually from 40°C to 90°C. Explain your answer.
27. What is the optimal temperature for the functionality of a human enzyme?