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Topic 3.6 Review Book
Enzymes
Name: _____________________
Topic 3 The Chemistry of Life
Topic 3.6: Enzymes (Textbook pages 52-62)
Key facts
1. The function of enzymes is to lower the activation energy needed for reactions to occur. By doing
this, the reactions may occur faster. Enzymes are organic catalysts. They are proteins.
2. The amino acids that make up these enzymes allow a tertiary and/or quaternary structure. Because
each enzyme has a specific amino acid sequence, enzymes have a specific three-dimensional shape.
3. The molecule an enzyme affects is known as its substrate.
4. The enzyme, because of its three-dimensional shape, has a region called the active site. It is the
shape of the active site that determines which substrate it is specific for.
5. Enzymes may not cause reactions to occur that would not happen on their own.
6. Higher temperatures will increase enzyme catalyzed reaction rates until too high a temperature is
reached. At this high temperature denaturation of the enzyme occurs and the effect of the enzyme
is stopped.
7. pH also will affect an enzymes reaction rate. At extreme pH levels, enzymes may be denatured, thus
stopping their effect.
8. Denaturation changes are usually permanent. Temperature and pH are the two most common
factors to cause denaturation.
9. Lactase is an enzyme that speeds up the breakdown of lactose, milk sugar. People without lactase
are said to be lactose intolerant and will experience intestinal distress when they ingest dairy
products.
10. By treating dairy products with lactase before ingestion, distress may be prevented in lactose
intolerant people.
11. Increasing the amount substrate in a chemical reaction will increase the reaction rate as long as
there are available active sites on enzyme molecules.
Complete the following.
1. What is the function of an enzyme?
2. How does an enzyme compare to a catalyst?
3. What is the specific part of the enzyme that attaches to a substrate?
4. How does the induced-fit model of enzyme specificity differ from the lock-and-key model?
Topic 3.6 Review Book
Enzymes
Name: _____________________
5. What general macromolecule are most enzymes?___________________
6. Why are enzymes globular and not fibrous proteins?
7. What factors help to determine the shape of an enzyme (protein), and therefore control their
extreme specificity toward substrates?
8. How do enzymes speed up chemical reactions?
9. What happens in denaturation?
10. What will happen to an enzyme’s effect when denaturation occurs?
11. Can an enzyme cause a reaction to occur that would not happen on its own?_____
12. Name two specific agents that may cause enzyme denaturation. Give an example of each.
13. With a graph with temperature as the x-axis and enzyme activity as the y-axis show the effect of
temperature. On the graph annotate, where denaturation occurs.
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Topic 3.6 Review Book
Enzymes
Name: _____________________
14. Similarly to number 13, show the effect of pH. On the graph, annotate where denaturation occurs.
15. Explain the effect of increasing substrate concentration of the rate of chemical reaction that is being
catalyzed by an enzyme.
16. What would the shape of the graph produced by number 78 be?
17. Explain the action of the enzyme lactase.
18. Some people are lactose intolerant. How might lactase be used to help people with this condition?
19. Besides the above function of helping lactose intolerant people, what are some other functions of
lactase?
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