Exam 8: Energy and Enzymes: an Introduction to Metabolism

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

The following question(s) are based on the reaction A + B ↔ C + D shown in the accompanying figure. -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 these 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 findings tell you about the mechanism of this protein?

The following question(s) are based on the reaction A + B ↔ C + D shown in the accompanying figure. -Which of the following in the figure would be the same in either an enzyme-catalyzed or a noncatalyzed reaction?

Which of the following is TRUE for all exergonic reactions?

Use the following information to answer the question(s) below. 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. -Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?

When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated?

A system at chemical equilibrium ________.

The mathematical expression for the change in free energy of a system is ΔG =ΔH − TΔS. Which of the following is (are) correct?

When 10,000 molecules of ATP are hydrolyzed to ADP and i in a test tube, about half as much heat is liberated as when a cell hydrolyzes the same amount of ATP. Which of the following is the best explanation for this observation?

Some of the drugs used to treat HIV patients are competitive inhibitors of the HIV reverse transcriptase enzyme. Unfortunately, the high mutation rate of HIV means that the virus rapidly acquires mutations with amino acid changes that make them resistant to these competitive inhibitors. Where in the reverse transcriptase enzyme would such amino acid changes most likely occur in drug-resistant viruses?

An important group of peripheral membrane proteins are enzymes such as the phospholipases that cleave the head groups of phospholipids. What properties must these enzymes exhibit?

The following question(s) are based on the reaction A + B ↔ C + D shown in the accompanying figure. -Which of the following represents the difference between the free-energy content of the reactants and the free-energy content of the products in the figure?

Zinc, an essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. The zinc most likely functions as ________.

Use the following information to answer the question(s) below. 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?

Whenever energy is transformed, there is always an increase in the ________.

Which of the following statements is TRUE about enzyme-catalyzed reactions?

The following question(s) are based on the reaction A + B ↔ C + D shown in the accompanying figure. -Which of the following represents the activation energy needed for the noncatalyzed reverse reaction, C + D → A + B, in the figure?

A solution of starch at room temperature does NOT readily decompose to form a solution of simple sugars because ________.

The following question(s) are based on the reaction A + B ↔ C + D shown in the accompanying figure. -Which of the following represents the activation energy required for a noncatalyzed reaction in the figure?

Living organisms increase in complexity as they grow, resulting in a decrease in the entropy of an organism. How does this relate to the second law of thermodynamics?