Bio CH. 6

In most exergonic reactions, before products can be formed, the reactants must first overcome a thermodynamic barrier known as the

activation energy of the reaction

The cellular process of synthesizing large molecules from smaller ones is defined as

anabolism

Cooperatively is a form of allosteric activation in which

binding of a substrate molecule to one active site in a multisubunit enzyme stimulates the binding of substrate molecules to the active sites of other subunits.

The active site of an enzyme is the region that

binds substrates for the enzyme.

The cellular process of breaking down large molecules into smaller ones is defined as

catabolism

A noncompetitive inhibitor decreases the rate of an enzymatic reaction by

changing the shape of the enzyme active site.

Zinc, an essential trace element for most organisms, is required in the active site of the enzyme carboxypeptidase in order for the enzyme to function properly. The zinc most likely functions as a(n)

cofactor necessary for enzyme activity.

A chemical reaction that has a positive ̇G is best described as

endergonic

The mechanism by which the end product of a metabolic pathway inhibits an enzyme that catalyzes an earlier step in the pathway is most precisely described as

feedback inhibition.

An enzyme-catalyzed reaction is conducted in a test tube with a fixed amount of enzyme. Increasing the substrate concentration in the test tube may overcome the effect of which of the following conditions?

presence of a fixed amount of a competitive inhibitor

Which of the following descriptions would be an example of potential energy?

the chemical bonds in a molecule of sucrose

Which of the following statements best describes the critical role that ATP plays in cellular metabolism?

ATP serves as an energy shuttle in the cell, coupling exergonic and endergonic reactions

Which of the following statements is representative of the second law of thermodynamics?

Cells require a constant input of energy to maintain their high level of organization.

Which of the following is a statement of the first law of thermodynamics?

Energy cannot be created or destroyed.

Which of the following statements regarding enzymes is true?

Enzymes increase the rate of a reaction by lowering the activation energy barrier.

Which of the following statements is a logical consequence of the second law of thermodynamics?

Every chemical reaction must increase the total entropy of the universe.

Hydrolysis of ATP releases energy, which ultimately results in the production of ADP and inorganic phosphate. What is commonly the immediate fate of the phosphate released by ATP hydrolysis in the cell?

It is attached to a substrate to form a phosphorylated intermediate

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

It is released to the environment

Why might a severe fever result in death if it is not brought under control?

It may alter the tertiary and quaternary structures of cellular enzymes.

Which of the following is the most comprehensive definition of metabolism in living organisms?

Metabolism consists of all the energy transformation reactions in an organism.

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

The rate of the reaction is greater than when the same reaction occurs in the absence of an enzyme.

Which of the following statements is true for all exergonic reactions?

The reaction proceeds with a net release of free energy.

Which of the following statements about a system at chemical equilibrium is true?

The system can do no work.