Chapter 6 Metabolism

What is changed in the reaction of the action of an enzyme?

Activation energy.

The process of stabilizing the structure of an enzyme in its active form by the binding of a molecule is an example of _________

Allosteric regulation

Which of the following correctly states the relationship between anabolic and catabolic pathways?

Anabolic pathways synthesize more complex organic molecules using the energy derived from catabolic pathways.

Which of the following metabolic processes can occur without a net influx of energy from some other process?

C6H12O6 + 6 O2 --> 6 CO2 + 6 H2O

Which of the following environments or actions would not affect the rate of an enzyme reaction? A. Heating B. Cooling C. Substrate concentration D. pH E. Lul none of these

E. Lul none of these.

If the entropy of a living organism is decreasing, which of the following is most likely to be occurring simultaneously?

Energy is being supplied to the organism.

Statement of enzyme functions.

Enzymes can lower the activation energy of reactions, but they cannot change the equilibrium point because they cannot change the net energy output.

Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as __________ is to _________

Exergonic; Endergonic

Which of the following is an endergonic process

Glucose + fructose → sucrose

What do the sign and magnitude of the ΔG of a reaction tell us about the speed of the reaction?

Neither the sign nor the magnitude of ΔG has anything to do with the speed of a reaction.

Organisms are described as thermodynamically open systems. Which of the following statements is consistent with this description?

Organisms acquire energy from, and lose energy to, their surroundings.

In general, the hydrolysis of ATP drives cellular work by __________.

Releasing of free energy that can be coupled with other reactions.

Most cells cannot harness heat to perform work because

Temperature is usually uniform throughout the cell.

Statement of enzyme inhibitors

The action of competitive inhibitors may be reversible or irreversible.

Which of the following statements about the active site of an enzyme correct?

The active site may resemble a groove or pocket in the surface of a protein into which the substrate fits

The binding of an allosteric inhibitor to an enzyme causes the rate of product formation by the enzyme to decrease. Which of the following best explains why this decrease occurs?

The allosteric inhibitor causes a structural change in the enzyme that prevents the substrate from binding at the active site.

Metabolic pathways in cells are typically far from equilibrium. Which of the following processes tend(s) to keep these pathways away from equilibrium?

The continuous removal of the products of a pathway to be used in other reactions and the input of free energy from outside the pathway

What does "induced fit" of an enzyme mean?

The enzyme changes its shape slightly as it binds the substrate.

What determines ΔG for a reaction?

The free energy of the reactants and the free energy of the products

Which of the following best characterizes the functional role of ATP in cellular metabolism?

The free energy released by ATP hydrolysis is coupled to endergonic processes via the formation of a phosphorylated intermediate.

The formation of glucose-6-phosphate from glucose is an endergonic reaction and would, therefore, be coupled to which of the following reactions or pathways?

The hydrolysis of ATP

A chemical reaction is designated as exergonic rather than endergonic when

The potential energy of the products is less than the reactants.

Enzyme activity is influenced by pH because _____

high or low pH may disrupt hydrogen bonding or ionic interactions and thus change the shape of the enzyme's active site

Much of the suitability of ATP as an energy intermediary is related to the instability of the bonds between the phosphate groups. These bonds are unstable because _________

the negatively charged phosphate groups vigorously repel one another and the terminal phosphate group is more stable in water than it is in ATP