QUIZ 8

If this is an enzyme-catalyzed reaction, how can the rate of this reaction be increased beyond the maximum velocity in this figure?

Increase the amount of enzyme.

How do living organisms create macromolecules, organelles, cells, tissues, and complex higher-order structures?

Living organisms create order locally, but the energy transformations generate waste heat that increases the entropy of the universe.

Firefly luciferase catalyzes the reaction luciferin + ATP ↔ adenyl-luciferin + pyrophosphate then the next reaction occurs spontaneously: adenyl-luciferin + O2 → oxyluciferin + H2O + CO2 + AMP + light What is the role of luciferase?

Luciferase lowers the transition energy of the reaction.

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

The glucose molecules lack the activation energy at room temperature.

A reaction has a ∆G of −5.6 kcal/mol. Which of the following would most likely be true?

The reaction would result in an increase in entropy (S) and a decrease in the energy content (H) of the system.

which of the following is an example of potential rather than kinetic energy?

a molecule of glucose

Adenosine monophosphate (AMP) activates the enzyme phosphofructokinase (PFK) by binding at a site distinct from the substrate binding site. This is an example of

allosteric activation.

which of the following is most similar in structure to ATP?

an RNA nucleotide

The hydrolysis of ATP: ATP + H2O → ADP + Pi is exergonic, with a ΔG of −7.3 kcal/mol under standard conditions. What is the source of the 7.3 kcal/mol released in this reaction?

breaking the terminal phosphate bond in ATP

which term more precisely described the cellular process of breaking down large molecule into smaller ones?

catabolism

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)

cofactor necessary for enzyme activity

increasing the substrate concentration in an enzymatic reaction could overcome which of the following?

competitive inhibition

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

competitive inhibitors

the second law of thermodynamics holds that

energy of one form is converted to a less concentrated form whenever energy is transformed or transferred

whenever energy is transformed, there is always an increase in the

entropy of the universe

Are most chemical reactions at equilibrium in living cells?

no

Which enzymes may translocate from the cytoplasm to associate with the cytoplasmic face of the plasma membrane in response to a signal?

phospholipid hydrolases

When sodium chloride (table salt) crystals dissolve in water, the temperature of the solution decreases. This means that, for dissociation of Na+ and Cl- ions,

the change in enthalpy (ΔH) is positive, but the change in entropy is greater.

When sodium chloride (table salt) crystals dissolve in water, the temperature of the solution decreases. This means that, for dissociation of Na+ and Cl- ions,

the change in enthalpy is positive, but the change in entropy is greater

which of the following statements is true about enzyme-catalyzed reactions?

the reaction is faster than the same reaction in the absence of the enzyme