You have isolated a previously unstudied protein, identified its complete structure in detail and determined that it catalyzes the breakdown of a large substrate. You notice it has two binding sites. One of theses is large, apparently the bonding site for the large substrate; the other is small, possibly a binding site for a regulatory molecule. What do these finding tell you about the mechanism of this protein?

You have isolated a previously unstudied protein, identified its complete structure in detail and determined that it catalyzes the breakdown of a large substrate. You notice it has two binding sites. One of theses is large, apparently the bonding site for the large substrate; the other is small, possibly a binding site for a regulatory molecule. What do these finding tell you about the mechanism of this protein?

a. it is probably an enzyme that works through allosteric regulation
b. it is probably an enzyme that works through competitive inhibition
c. it is probably a cell membrane transport protein-like an ion channel
d. it is probably a structural protein that is involved in cell-to-cell adhesion

Answer: A

With respect to the enzyme that converts X to Y, substance A functions as _____.

With respect to the enzyme that converts X to Y, substance A functions as _____.

a. a competitive inhibitor
b. an allosteric inhibitor
c. the substrate
d. an intermediate

Answer: B

What is substance X?

What is substance X?

a. the product
b. a substrate
c. an allosteric inhibitor
d. an intermediate





Answer: B

In the figure, why does the reaction rate plateau at higher reactant concentrations?

In the figure, why does the reaction rate plateau at higher reactant concentrations?

a. the reaction nears equilibrium at high reactant concentrations
b. the rate of the reverse reaction increases with reactant concentration
c. feedback inhibition by product occurs at high reactant concentrations
d. most enzyme molecules are occupied by substrate at high reactant concentrations

Answer: D

A noncompetitive inhibitor decreases the rate of an enzyme reaction by____.

A noncompetitive inhibitor decreases the rate of an enzyme reaction by____.

a. binding at the active site of the enzyme
b. acting as a coenzyme for the reaction
c. changing the free energy change of the reaction
d. changing the shape of the enzyme's active site

Answer: D

According to the induced fit hypothesis of enzyme catalysis, ______.

According to the induced fit hypothesis of enzyme catalysis, ______.

a. the binding of the substrate changes the shape of the enzyme's active site
b. some enzymes change their structure when activators bind to the enzyme
c. the active site created a microenvironment ideal for the reaction
d. the binding of the substrate depends on the shape of the active site

Answer: A