AP Biology : Understand the effect of environment of the enzyme
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Example Question #1 : Enzymes
Which of the following factors has an effect on the rate at which enzymes catalyze a reaction?
Temperature of environment
Concentration of substrate and enzyme
All of these factors have an effect on the rate at which enzymes catalyze a reaction
pH of environment
All of these factors have an effect on the rate at which enzymes catalyze a reaction
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.
Example Question #2 : Enzymes
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
It will decrease the equilibrium constant
It will cause reaction to go slower
It will increase the equilibrium constant
It will have no effect on the equilibrium constant
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.
Example Question #3 : Enzymes
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?
Increasing the temperature will decrease the activation energy
Heat will shift the equilibrium to the left, favoring the reactant side
Increasing the temperature will increase the activation energy
High temperatures will change the shape and functionality of proteins
High temperatures will change the shape and functionality of proteins
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.
Example Question #4 : Enzymes
Which of the following characteristics affects the function of an enzyme?
pH
None of these
Temperature
All of these
Substrate concentration
All of these
Temperature, pH, and substrate concentration all affect the function of an enzyme; therefore, the correct answer is all of these.
Example Question #5 : Enzymes
Which of the following statements about enzymes is correct?
They function under a narrow pH range
They always require a coenzyme
They are consumed in the reaction
They are polymers of carbohydrates
They are used to create ATP
They function under a narrow pH range
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.
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