Bio I Lab Quiz 5: Enzymes

Which of the following is true of enzymes?

Enzymes increase the rate of chemical reaction by lowering activation energy barriers.

Rate of an enzyme -catalyzed reaction as a function of varying reactant concentration, with the concentration of enzyme constant. In the figure, why does the reaction rate plateau at higher reactant concentrations?

Most enzyme molecules are occupied by substrate at high reactant concentrations.

Which of the following is true for all exergonic reactions?

The reaction proceeds with a net release of free energy.

A series of enzymes catalyze the reaction X → Y → Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme.What is substance X?

a substrate

Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's _____.

activation energy

A series of enzymes catalyze the reaction X → Y → Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme.

an intermediate

How might a change of one amino acid at a site, distant from the active site of an enzyme, alter an enzyme's substrate specificity?

by changing the shape of an enzyme

Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?

catabolism (catabolic pathways)

For the enzyme- catalyzed reaction shown in the figure, if the initial reactant concentration is 1.0 micromolar, which of these treatments will cause the greatest increase in the rate of the reaction?

doubling the enzyme concentration

The active site of an enzyme is the region that _____.

is involved in the catalytic reaction of the enzyme