2.8.3 Enzyme Characteristics

Question 1

enzymes

Answer 1

• have several characteristics that have been used to construct a model for the mechanism of their action
• sensitive to temperature. As the temperature increases, enzymes work faster. As the temperature
  decreases, enzymes work slower
• sensitive to pH. pH is the measurement of H+ ions in solution. Different enzymes may work within a different pH range.
• can be inhibited by certain chemicals. These inhibitors can be temporary or permanent.
• can be promoted or enhanced by other chemicals
• are specific. One enzyme will have a specific substrate. A substrate is the particular chemical that the enzyme acts on
• are reversible—enzymatic reactions can work both ways

Question 2

If an enzyme that breaks down carbohydrates is placed in a solution of proteins, what will happen?

Answer 2

• Nothing will happen

Question 3

In general, enzymes

Answer 3

• function most quickly at an intermediate temperature

Question 4

True or false?

Molecules exist that can inhibit enzyme activity; however, no known molecules can promote enzyme activity.

Answer 4

• false

Question 5

Which statement about enzymes is not true?

a. Enzyme action can be blocked with another chemical compound.
b. Enzymes work on forward and reverse reactions.
c. Enzymes are nonspecific and one enzyme may catalyze many reactions by reacting with many substrates.
d. Enzymes are sensitive to changes in pH and temperature.

Answer 5

• c. Enzymes are nonspecific and one enzyme may catalyze many reactions by reacting with many substrates

Question 6

If abcd-ase is the enzyme used to catalyze the reaction
A + B → C + D,
what enzyme would catalyze the reaction
C + D → A + B?

Answer 6

• abcd-ase

Question 7

Which of the following statements regarding pH is correct?

Answer 7

• Changing the hydronium ion concentration changes the rate of biological reactions

Question 8

Which of the following does not apply to enzymes?

a. They are highly specific.
b. Their structure influences their function.
c. They participate in almost all biochemical reactions.
d. They increase the energy required to activate the reaction.

Answer 8

• d. They increase the energy required to activate the reaction

Question 9

In an enzyme catalyzed reaction that breaks down a sucrose molecule into a glucose and a fructose molecule, what is the sucrose molecule called?

Answer 9

• the substrate

Question 10

Which of the following statements regarding enzymes is false?

a. They change the rate of a reaction.
b. Certain chemicals inhibit them.
c. Different enzymes can have widely different optimal temperatures.
d. The optimal pH for pepsin and trypsin is the same

Answer 10

• d. The optimal pH for pepsin and trypsin is the same

Question 11

Which environmental factors can affect an enzyme?

Answer 11

• temperature and pH