BIO lecture 9 quiz

Wood is extremely flammable, so why don't trees spontaneously burst into flame?

At room temperature, the molecules in wood do not have sufficient energy to overcome the activation energy barrier necessary for this reaction to occur.

Firefly luciferase catalyzes the reaction: What is the role of luciferase?

Luciferase lowers the transition energy of the reaction.

For the reaction described in the figure shown below, which of the following represents the difference between the free energy content of the reactants and the free energy content of the products?

Arrow D

For the reaction described in the figure shown below, which of the following represents the activation energy barrier for the noncatalyzed reaction?

arrow C

For the reaction depicted in the figure below, the activation energy barrier for converting C and D to A and B via the non-catalyzed reaction is represented by

arrow E

Which of the following statements describes enzyme cooperativity?

A substrate molecule bound to the active site of one subunit alters the conformation of that subunit and of the other subunits in a multi-subunit enzyme in such a way that the other subunits are able to bind substrate molecules more easily.

Which of the following statements about ATP and ADP is TRUE?

ATP acts as an allosteric inhibitor of many enzymes in catabolic pathways while ADP acts as an allosteric activator of many enzymes in catabolic pathways.

A competitive inhibitor for a particular enzyme Select one: a. will have a 3-dimensional structure that is similar to that of the enzyme's substrate b. will compete with the enzyme's substrate for binding to the enzyme's active site c. All of these answers are correct. d. will be more effective the higher its concentration

All of these answers are correct.

If ATP levels increase and ADP levels decrease

All of these answers are correct.

Which of the following statements comparing allosteric regulators and non-competitive inhibitors is TRUE?

Allosteric regulators may increase or decrease an enzyme's activity level.

Which of the following statements is TRUE? Select one: a. Inhibition of anabolic enzymes by ATP is an example of feedback inhibition. b. Inhibition of catabolic enzymes by ADP is an example of feedback inhibition. c. Inhibition of catabolic enzymes by ATP is an example of feedback inhibition. d. All of these answers are correct.

Inhibition of catabolic enzymes by ATP is an example of feedback inhibition.

For the reaction described in the figure shown below, which of the following best describes the reaction?

The amount of free energy released as a result of the catalyzed reaction is indicated by arrow "D".

Which of the following are TRUE for anabolic pathways?

They consume energy to build up polymers from monomers

Which of the following is likely to lead to an increase in the concentration of ATP in a cell?

a decrease in a cell's anabolic activity

Which of the following is an example of cooperativity?

a substrate molecule binding at one unit of a tetramer allowing faster substrate binding at each of the other three subunits.

A series of enzymes catalyzes the series of reactions shown below. 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. Substance A functions as

an allosteric inhibitor

How does a noncompetitive inhibitor decrease the rate of an enzyme reaction?

by increasing the activation energy barrier of the reaction

The oxidation of glucose to CO2 and H2O is highly exergonic: ∆G = -636 kcal/mol. Why doesn't glucose spontaneously combust?

c. The glucose molecules lack the activation energy at room temperature.

Kinases are enzymes that catalyze phosphorylation (the addition of a phosphate group) whereas phosphatases are enzymes that catalyze the removal of phosphate groups. A cell can use these enzymes like on-off switches for the activities of various proteins. Which of the following is probably involved?

changes in a protein's charge leading to conformational changes

When you have a severe fever, what may be a grave consequence if this is not controlled?

changes in the folding of enzymes

Vioxx and other prescription nonsteroidal anti-inflammatory drugs (NSAIDs) are potent inhibitors of the cyclooxygenase-2 (COX-2) enzyme. High substrate concentrations reduce the efficacy of inhibition by these drugs. These drugs are

competitive inhibitors

A series of enzymes catalyzes the series of reactions shown below. 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. Substance A functions in

feedback inhibition

You notice that many of the anabolic reactions in a cell have speeded up. Upon further characterization of the cell, you are NOT surprised to find that

the ATP levels in the cell are high and the ADP levels are low.

You notice that many of the catabolic reactions in a cell have speeded up. Upon further characterization of the cell, you are NOT surprised to find that

the ATP levels in the cell are low and the ADP levels are high.