BIO101 EXAM 2REVIEW 2March 25th, 2017

1) Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?
A) catalysis B) metabolism C) anabolism D) dehydration E) catabolism

2) Which of the following is most similar in structure to ATP?
A) a pentose sugar B) a DNA nucleotide C) an RNA nucleotide D) an amino acid with three phosphate groups attached E) a phospholipid

3) Which of the following statements is true about enzyme-catalyzed reactions?
A) The reaction is faster than the same reaction in the absence of the enzyme.
B) The free energy change of the reaction is opposite from the reaction that occurs in the absence of the enzyme. C) The reaction always goes in the direction toward chemical equilibrium. D) Enzyme-catalyzed reactions require energy to activate the enzyme. E) Enzyme-catalyzed reactions release more free energy than noncatalyzed reactions.

4) Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's
A) entropy. B) activation energy. C) endothermic level. D) equilibrium point. E) free-energy content.

5) Which of the following statements regarding enzymes is true?
A) Enzymes increase the rate of a reaction by making the reaction more exergonic. B) Enzymes increase the rate of a reaction by lowering the activation energy barrier . C) Enzymes increase the rate of a reaction by reducing the rate of reverse reactions. D) Enzymes change the equilibrium point of the reactions they catalyze. E) Enzymes make the rate of a reaction independent of substrate concentrations.

6) The active site of an enzyme is the region that
A) binds allosteric regulators of the enzyme. B) is involved in the catalytic reaction of the enzyme . C) binds noncompetitive inhibitors of the enzyme. D) is inhibited by the presence of a coenzyme or a cofactor.

7) According to the induced fit hypothesis of enzyme catalysis, which of the following is correct?
A) The binding of the substrate depends on the shape of the active site. B) Some enzymes change their structure when activators bind to the enzyme. C) A competitive inhibitor can outcompete the substrate for the active site. D) The binding of the substrate changes the shape of the enzyme's active site.
E) The active site creates a microenvironment ideal for the reaction.

8) Mutations that result in single amino acid substitutions in an enzyme
A) can have no effect on the activity or properties of the enzyme. B) will almost always destroy the activity of the enzyme. C) will often cause a change in the substrate specificity of the enzyme. D) may affect the physicochemical properties of the enzyme such as its optimal temperature and pH. E) may, in rare cases, cause the enzyme to run reactions in reverse.

9) Increasing the substrate concentration in an enzymatic reaction could overcome which of the following?
A) denaturization of the enzyme B) allosteric inhibition C) competitive inhibition D) saturation of the enzyme activity E) insufficient cofactors

10) Which of the following is true of enzymes?
A) Nonprotein cofactors alter the substrate specificity of enzymes.
B) Enzyme function is increased if the 3-D structure or conformation of an enzyme is altered.
C) Enzyme function is independent of physical and chemical environmental factors such as pH and temperature. D) Enzymes increase the rate of chemical reaction by lowering activation energy barriers . E) Enzymes increase the rate of chemical reaction by providing activation energy to the substrate.

11) Zinc, an essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. The zinc most likely functions as a(n)
A) competitive inhibitor of the enzyme. B) noncompetitive inhibitor of the enzyme. C) allosteric activator of the enzyme. D) cofactor necessary for enzyme activity. E) coenzyme derived from a vitamin.

12) In order to attach a particular amino acid to the tRNA molecule that will transport it, an enzyme, an aminoacyl- tRNA synthetase , is required, along with ATP. Initially, the enzyme has an active site for ATP and another for the amino acid, but it is not able to attach the tRNA. What must occur in order for the final attachment to occur?
A) The ATP must