Clicker Qu - Exam 3

Based on the reaction coordinate diagram shown below, which reaction occurs at a higher speed?

a. The one described by the blue curve

b. The one described by the red curve

c. They are equal

d. This is a bad question

The one described by the red curve

Which of the following is TRUE about enzymes?

a. They shift the equilibrium toward product

b. They speed up only the S → P reaction

c. They speed up both S → P and P → S

d. They slow down only the P → S reaction

They speed up both S → P and P → S

The presence of an enzyme:

a. Lowers the activation energy of the reaction

b. Increases the activation energy of the reaction

c. Reduces the energy differences of the two ground states

d. Increases the energy differences of the two ground states

Lowers the activation energy of the reaction

Which is TRUE about transition state?

a. It has the lowest free energy along the reaction coordinate

b. It is a long-lived state

c. It often contains partial bonds

d. It binds to the enzyme with less tightly than does the substrate state

e. It refers to any intermediate states between the two ground states

It often contains partial bonds

Which is NOT a mechanism by which enzymes catalyze biochemical reactions?

a. They provide catalytically active groups

b. They bind and orient substrates to facilitate the reaction

c. They bind the transition state more strongly than the

substrate

d. They raise the temperature of the reaction

They raise the temperature of the reaction

Which chymotrypsin structural feature functions primarily by forming hydrogen bonds to stabilize the negative charge of the tetrahedral intermediate?

a. The oxyanion hole

b. The catalytic triad

c. The substrate binding pocket

d. The specificity (hydrophobic) pocket

The oxyanion hole

Which of the following structural elements interacts with the aromatic side chain immediately preceding the scissile bond of the substrate?

a. The oxyanion hole

b. The catalytic triad

c. The substrate binding pocket

d. The specificity pocket

The specificity pocket

Which is true about the chymotrypsin-catalyzed reaction mechanism?

a. There are two tetrahedral intermediates formed

b. There is an alkoxide ion that acts as a nucleophile

c. There is a hydroxide ion that acts as a

nucleophile

d. All of the above

All of the above

Which is NOT a role of the catalytic His in chymotrypsin?

a. Generate the Ser alkoxide ion

b. Activate a H2O molecule for nucleophilic attack

c. Protonate the leaving peptide after peptide bond breakage

d. Determine the specificity of the reaction

Determine the specificity of the reaction

The influenza drug oseltamivir (Tamiflu)

a. Is the natural substrate for neuraminidase

b. Is the transition state of the natural substrate for neuraminidase

c. Is a synthetic compound resembling the transition state of the substrate for neuraminidase

d. Activates neuraminidase

Is a synthetic compound resembling the transition state of the substrate for neuraminidase

Abzymes are:

a. Antibodies that bind to the transition state of a reaction

b. Suicide inhibitors of a reaction

c. Enzymes that catalyze the production of antibodies

d. All of the above

Antibodies that bind to the transition state of a reaction