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Tutorial Chapter %: Cell metabolism

Correctly complete the following

1. _______________ is the energy needed to start a chemical reaction.

2. The amino acid sequence of a polypeptide chain best describes the _______________

structure of the polypeptide chain.

3. The substrate bonds to a specific area on the enzyme molecule known as the enzyme's

_______________.

4. Compounds similar in shape to an enzyme's substrate, that can compete with the

substrate molecules by binding with the active site of the enzyme are said to be

_______________.

5. The optimum pH for most human metabolic enzyme catalyzed reactions is _____.

6. The optimum temperature for most human metabolic enzyme catalyzed reactions is

_____ C.

7. An inactive form of an enzyme is called a(n) __________________.

Multiple Choice Section:

Choose the response which best completes the following statements or answers the

following questions.

1. Which is the optimum pH of most human enzymes? (1.) 1 (2.) 2 (3.) 5 (4.) 7 (5.)

10

2. The lock and key model of enzyme action illustrates that a particular enzyme

molecule (1) forms a permanent enzyme-substrate complex (2) may be destroyed and

resynthesized several times (3) interacts with a specific type of substrate molecule (4)

reacts at identical rates under all conditions3. An enzyme-substrate complex may result from the interaction of molecules of (1)glucose and lipase (2) fat and amylase (3) sucrose and maltase (4) protein and protease

4. The part of the enzyme molecule into which the substrate fits is called the (1) active

site (2) coenzyme (3) polypeptide (4) protease

5.. Which of the following variable is LEAST likely to affect an enzymes rate of

reaction? (1) temperature (2) pH (3) carbon dioxide concentration (4) enzyme

concentration

6. Which would least affect the effectiveness of an enzyme? (1.) temperature (2.)

concentration of the substrate (3.) concentration of the enzyme (4.) original activationenergy of the system (5.) pH

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7. Which is most similar to the process of competitive inhibition? (1.) When you are

about to park your car in your spot, a bulldozer comes along and smashes your car

away from the spot. (2.) When you arrive at work in the morning, you are unable to

park your car in your assigned parking spot because someone has placed a giant cement

block in front of your spot. (3.) When you arrive at work in the morning, you areunable to park your car in your assigned parking spot because the car of the person

next to you has taken up just enough space that you can not fit your own car in. (4)

When you arrive at work in the morning, you are unable to park your car in your

parking spot, because someone with a car exactly like yours has already taken your

spot, leaving you nowhere to park your car.

8. Which of the following is characteristic of enzymes?

1) They lower the energy of activation of a reaction by binding the substrate.

2) They raise the energy of activation of a reaction by binding the substrate.

3) They lower the amount of energy present in the substrate.

9. An enzyme is generally named by adding ____ to the end of the name of the _____.

1) "-ose". cell in which it is found 2) "-ase". cell in which it is found

3) "-ose". substrate 4) "-ase". substrate 5) "-ase". coenzyme

10. Which statement describes the currently accepted theory of how an enzyme and its

substrate fit together?

1) As the product is released, the enzyme breaks down.

2) The enzyme is like a key that fits into the substrate, which is like a lock.

3) The active site is permanently changed by its interaction with the substrate.

4) As the substrate binds to the enzyme, the shape of the enzyme site changes to

accommodate the reaction.

11. Which statement is Not true about the effects of various conditions on the activity of

an enzyme?

1) Higher temperatures generally increase the activity of an enzyme up to a point.

2) Above a certain range of temperatures, the protein of an enzyme is denatured.

3) A change in pH can cause an enzyme to be inactivated.

4) An enzyme's activity is generally reduced by an increase in substrate concentration.

5) When sufficient substrate is available, the active site will nearly always by occupied.

12. Which statement is Not true about enzyme inhibition?1) In competitive inhibition, the inhibitor binds to the active site of the enzyme.

2) In noncompetitive inhibition, the inhibitor binds to the allosteric site of the substrate.

3) In irreversible inhibition, a poison binds to the enzyme so that it can never work

again.

4) Most inhibitors act in a reversible fashion.

5) All of the above statements are true.

13. The active site of an enzyme

1) is similar to that of any other enzyme.

2) is the part of the enzyme where its substrate can fit.

3) can be used over and over again.4) is not affected by environmental factors like pH and temperature.

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5) Both B and C are correct.

14. An allosteric site on an enzyme is

1) the same as the active site. 2) nonprotein in nature.

3) where ATP attaches and gives up its energy.

4) often involved in feedback inhibition. 5) All of these are correct.

15. A student conducts an experiment to test the efficiency of a certain enzyme. Which

would probably not result in a change in the enzyme's efficiency? 1) Bringing the

temperature of the experimental setup from 20 degrees C to 50 degrees C.

2) Adding an acidic solution to the setup. 3) Adding more substrate but not enzyme.

4) Placing the substrate and enzyme in a container with double the capacity.

5) Adding enzyme but not substrate.

16. Which of the following statements about enzymes is Not True?

1) Competitive inhibitors act away from the active site.

2) Allosteric inhibitors act away from the active site.3) Allosteric inhibitors can change the size of the active site.

4) Competitive inhibitors usually resemble the substrate.

5) Noncompetitive inhibitors are allosteric inhibitors.

17. In noncompetitive inhibition, the allosteric inhibitor

1) attaches to the active site, preventing the substrate from attaching there.

2) attaches to the substrate, preventing it from attaching to the active site.

3) changes the pH of the environment, thus preventing enzyme-substrate complex

formation.

4) causes the substrates to polymerize, preventing individual enzyme-substrate

attachment.

5) attaches to the enzyme at a site away from the active site, altering the shape of the

enzyme.

18. Which of the following statements is Not True about all enzymes?

1) are proteins. 2) lower the activation energy of reactions.

3) operate at the same optimum pH.

4) can be identified because their names end in - ase.

5) require a coenzyme/cofactor to work effectively.

19. The minimum amount of energy needed for a process to occur is called the1) minimal energy theory 2) process energy 3) kinetic energy 4) activation energy 5)

None of the above.

20. An inhibitor that changes the overall shape and chemistry of an enzyme is known as

a(n)

1) allosteric inhibitor 2) competitive inhibitor 3) steric inhibitor 4) noncompetitive

inhibitor 5) None of the above.