Understand the effect of environment of the enzyme

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AP Biology › Understand the effect of environment of the enzyme

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1

Consider the reaction:

This reaction is catalyzed by an enzyme called carbonic anhydrase. Which of the following will result from increasing the concentration of carbonic anhydrase?

It will have no effect on the equilibrium constant

CORRECT

It will cause reaction to go slower

0

It will decrease the equilibrium constant

0

It will increase the equilibrium constant

0

Explanation

Enzymes are catalysts that help a reaction proceed faster. Increasing the concentration of carbonic anhydrase will not cause the reaction to go slower. Recall that catalysts (in this case carbonic anhydrase) do not alter the equilibrium of a reaction. They simply speed up the process so that equilibrium can be achieved more quickly. Increasing or decreasing the equilibrium constant means that there is a change in the equilibrium state of the reaction.

The equilibrium constant can only be affected by temperature changes or pressure changes, if there is a gas involved in the reaction. Catalysts affect the rate constant, which is dependent on activation energy. By decreasing activation energy, catalysts can increase the rate constant and allow a reaction to proceed faster.

2

In non-physiological reactions an increase in temperature will increase the reaction rate; however, in physiological reactions there is an optimum temperature at which an enzyme operates. Increasing the temperature beyond this will not increase enzyme activity or reaction rate. What explains this phenomenon?

High temperatures will change the shape and functionality of proteins

CORRECT

Increasing the temperature will increase the activation energy

0

Increasing the temperature will decrease the activation energy

0

Heat will shift the equilibrium to the left, favoring the reactant side

0

Explanation

There is an optimum temperature at which an enzyme is most effective. Decreasing or increasing the temperature from the optimum will lead to denaturation of proteins, which will affect their functionality. Most protein structure is dependent on non-covalent intermolecular forces, such as hydrogen bonding and hydrophobic interactions. Heat can disrupt these forces, causing the protein to lose its structure, which leads to a loss of functionality.

You can eliminate the answer choices about activation energy because changing temperature will have no effect on the activation energy. Adding heat could shift the equilibrium to the right or left, depending on whether the reaction is exothermic or endothermic.

3

Which of the following characteristics affects the function of an enzyme?

All of these

CORRECT

Temperature

0

Substrate concentration

0

pH

0

None of these

0

Explanation

Temperature, pH, and substrate concentration all affect the function of an enzyme; therefore, the correct answer is all of these.

4

Which of the following statements about enzymes is correct?

They function under a narrow pH range

CORRECT

They always require a coenzyme

0

They are used to create ATP

0

They are consumed in the reaction

0

They are polymers of carbohydrates

0

Explanation

The correct answer to this question is they function under a narrow pH range.

Enzymes do indeed function under a narrow pH range. A narrow pH range is needed because enzymes speed up reactions by lowering the activation energy and in order to do this very specific conditions must be met. Coenzymes are not always needed and they are certainly not consumed in a reaction. Enzymes also are proteins so they are polymers of amino acids, not carbohydrates. Also enzymes have no part in the creation of ATP.

5

Which of the following factors has an effect on the rate at which enzymes catalyze a reaction?

All of these factors have an effect on the rate at which enzymes catalyze a reaction

CORRECT

Temperature of environment

0

pH of environment

0

Concentration of substrate and enzyme

0

Explanation

The temperature and pH of the environment, as well as the concentration of the substrate and enzyme, all affect the rate at which an enzyme catalyzes a reaction. As a result, enzymes have optimal conditions in which they can work at peak efficiency.