Topic 2.5 Enzymes Review
**Review all the “understanding” statements at the beginning of each section.
Key facts
 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.
 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.
 The molecule an enzyme affects is known as its substrate.
 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.
 Enzymes may not cause reactions to occur that would not happen on their own.
 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.
 pH also will affect an enzymes reaction rate. At extreme pH levels, enzymes may be denatured, thus
stopping their effect.
 Denaturation changes are usually permanent. Temperature and pH are the two most common factors to
cause denaturation.
 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.
 By treating dairy products with lactase before ingestion, distress may be prevented in lactose intolerant
people.
 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 type of macromolecule is an enzyme?
2) What do you call the substance the enzyme works on?
4) The area or region where the enzyme and substrate come together is called the _________ _________.
5) Be able to draw a graph and explain what effect pH, temperature and substrate concentration have on
enzyme activity.
6) What factors cause an enzyme to become denatured?
7) What is an immobilized enzyme?
8) Describe how immobilized lactase can help people who are lactose intolerant.
9. What is the function of an enzyme?
10. How does an enzyme compare to a catalyst?
11. How does the induced-fit model of enzyme specificity differ from the lock-and-key model?
12. Why are proteins globular and not fibrous proteins?
13. What factors help to determine the shape of an enzyme (protein), and therefore control their extreme
specificity toward substrates?
14. How do enzymes speed up chemical reactions?
15. What happens in denaturation?
16. What will happen to an enzyme’s effect when denaturation occurs?
17. Can an enzyme cause a reaction to occur that would not happen on its own?_____
18. Name two specific agents that may cause enzyme denaturation. Give an example of each.
19. Explain the action of the enzyme lactase.
20. Some people are lactose intolerant. How might lactase be used to help people with this condition?
21. Besides the above function of helping lactose intolerant people, what are some other functions of lactase?
22. Describe some common uses of enzymes in industry.