Enzyme and rate analyses

Question 1

1. The enzyme 2.2.8.11 is a(n):

a. oxidoreductase.
b. transferase.
c. hydrolase.
d. lyase.
e. isomerase.
f. ligase

Answer 1

b. transferase.

Question 2

2. A disulfide bond in a protein is an example of:
   a. primary structure.
   b. secondary structure.
   c. tertiary structure.
   d. quaternary structure

Answer 2

b. secondary structure

Question 3

3. The active site of an enzyme is:

a. small compared to the entire enzyme.
b. usually in the center of the enzyme.
c. not specific for inhibitors.
d. typically only involves a few continuous bases along
the primary structure.

Answer 3

a. small compared to the entire enzyme.

Question 4

4. Which of the following can affect the rate of an enzyme catalyzed reaction?

a. Enzyme concentration
b. Substrate concentration
c. pH
d. Reaction temperature
e. All of the above

Answer 4

e. All of the above

Question 5

5. Km is:

a. the enzyme concentration that results in 50% of the
maximal reaction rate.
b. a property of an enzyme and substrate under certain
conditions.
c. a property of an enzyme irrespective of the substrate.
d. a property of a substrate irrespective of the enzyme

Answer 5

a. the enzyme concentration that results in 50% of the
maximal reaction rate.

Question 6

6. Which statement is correct?

a. Either the enzyme or the coenzyme, but not both, are
consumed during an enzymatic reaction.
b. An enzyme without a prosthetic group attached is
referred to as a coenzyme.
c. Coenzymes may contain vitamins.
d. All of the above statements are correct.

Answer 6

c. Coenzymes may contain vitamins.

Question 7

7. An enzyme assay determined by a single measurement
   taken at the termination of the enzymatic reaction is
   referred to as a:

a. fixed-time assay.
b. terminator assay.
c. kinetic assay.
d. continuous-monitoring assay.

Answer 7

a. fixed-time assay.

Question 8

8. A reactant in a catalysis reaction that binds to the enzyme’s
   active site is the:

a. enzyme.
b. product.
c. substrate.
d. coenzyme

Answer 8

c. substrate.

Question 9

9. An international unit (U) of enzyme activity is the amount of enzyme that will catalyze the reaction of:

a. one micromole of substrate per minute.
b. one mole of substrate per second.
c. one micromole of enzyme per hour.
d. one millimole of substrate per minute

Answer 9

a. one micromole of substrate per minute.

Question 10

10. In what kind of inhibition is the inhibitor usually a structural analog of the substrate?

a. Competitive
b. Noncompetitive
c. Uncompetitive
d. Racemic mirroring

Answer 10

a. Competitive

Question 11

11. In an analytical enzymatic measurement of substrate, an
    enzyme reaction is accompanied by a change in absorbance of one component of the assay system. If this
    change is continuously monitored while it is occurring,
    the reaction is referred to as a(n):

a. fixed-time reaction.
b. end point assay.
c. rate-limiting reaction.
d. self-indicating reaction.

Answer 11

d. self-indicating reaction.