High School Biology : Understanding Inhibitors
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Example Questions
Example Question #11 : Protein Function
Which of the following statements is true concerning competitive inhibitors?
They change the substrates that can enter the active site of the enzyme
They temporarily bind to the active site of an enzyme
They permanently bind to the active site of an enzyme
They temporarily alter the shape of the active site of the enzyme
They temporarily bind to the active site of an enzyme
A competitive inhibitor will temporarily bind to the active site on an enzyme. This forbids substrates from entering the enzyme's active site and stops the enzyme from catalyzing the reaction.
In contrast, non-competitive inhibitors will bind to other regions of the enzyme, outside of the active site, and cause the active site to change shape. This change then prevents substrates from binding.
Example Question #2 : Understanding Inhibitors
What inhibitor type prevents catalysis by noncovalently binding to an enzyme's active site?
Uncompetitive inhibitor
Irreversible inhibitor
Competitive inhibitor
Noncompetitive inhibitor
Competitive inhibitor
Inhibitors are able to prevent maximum enzymatic rates in a variety of ways. Some inhibitors, like noncompetive inhibitors, are able to attach at a point on the enzyme and alter its conformation. Competitive inhibitors, however, bind directly at the active site, which prevents substrate from entering the enzyme.
Competitive inhibitors are the only inhibitor type to bind directly to the enzyme actve site.
Example Question #3 : Understanding Inhibitors
Some enzymes have a direct function of catalyzing a reaction within a cell. Other enzymes simply change their fellow enzymes.
Enzyme X is found in a certain cell and is normally active. At a certain point, the cell creates enzyme X inhibitor, which inhibits enzyme X. What can be concluded about the cell following the synthesis of the inhibitor?
There is less of enzyme X, but its functionality is enhanced
There is the same amount of enzyme X, but its functionality will be lessened
There is less of enzyme X, which will decrease its relative functionality
The inhibitor destroys enzyme X
There is the same amount of enzyme X, but its functionality is enhanced
There is the same amount of enzyme X, but its functionality will be lessened
An inhibitor binds to an enzyme and stops it from performing its normal function. It does not destroy the enzyme and does not change the amount present, but it decreases the amount of activity of that enzyme.
Example Question #4 : Understanding Inhibitors
An inhibitor changes an enzyme's function by which of the following mechanisms?
Binding to the enzyme and stopping it from performing its function
Destroying the enzyme so that it cannot perform its function
Destroying the enzyme's substrate, so the enzyme cannot perform its function
Stoping production of the enzyme so that there is less effective enzyme function
Exporting the enzyme out of the cell so that it cannot perform its function
Binding to the enzyme and stopping it from performing its function
Most inhibitors work by binding to an enzyme so that the substrate cannot bind to the enzyme, and thus the function cannot take place.
Inhibitors generally affect functionality by interfering with the reaction without altering the amount of substrate or enzyme molecules.
Example Question #5 : Understanding Inhibitors
An alien cell forms the byproduct, Compoound A. Compound A acts as an inhibitor for the formation of Protien B. Scientists discovered that if they increased the concentration of the building blocks for Protein B, the inhibitory properties of Compound A could be negated. Which process explains this mechanism?
Enzyme breakdown
Competivie inhibition by Compound A
Allosteric regulation by Compound A
Allosteric regulation by an unknown compound
None of the other answer choices
Competivie inhibition by Compound A
The correct answer is competitive inhibiiton by Compound A. You can gather that because Compound A's inhibitory properties were negated, the reaction rate increased. As a result, competitive inhibition by Compound A takes place since the reaction rate increases as reactant concentration increases which occurs regardless of inhibitor presence (assuming enough enzymes are present). In contrast, the concentration of reactants would be irrelevant in the case of allosteric regulation either by Compound A or an unknown compound. Enzyme Breakdown would not result in an increase of the reaction rate.
Example Question #6 : Understanding Inhibitors
If a noncompetitive inhibitor in solution were affecting enzyme activity, then what would be the effect of adding additional substrate to the enzyme solution?
There would be a large decrease in enzymatic activity
There would be a small decrease in enzymatic activity
There would be a small increase in enzymatic activity
There would be a large increase in enzymatic activity
There would be no change in enzymatic activity
There would be no change in enzymatic activity
A noncompetitive inhibitor does not directly compete with the substrate binding to the substrate-binding site of an enzyme. The inhibitor instead binds to another site on the enzyme, which alters the enzyme's affinity for its substrate; therefore, adding more substrate would not cause a change in enzymatic activity.
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