Enzymes Flashcards
What is the function of an enzyme? Explain by referring to the enzyme’s impact on the energy required for a chemical reaction and the rate of the reaction.
An enzyme reduces the activation energy of a chemical reaction. The lower activation energy means the rate of the chemical reaction increases, as less energy input is needed to begin the chemical reaction.
What happens in the course of an enzyme catalysed chemical reaction? Refer to the enzyme, substrate, active site, enzyme-substrate complex and product in your answer.
The substrate (reactant) binds to the active site of the enzyme creating the enzyme substrate complex. Once in the enzyme-substrate complex, the substrate is converted to product. The product releases from the enzyme allowing the enzyme to be reused in another chemical reaction.
Why is it that each different chemical reaction requires a different enzyme? Hint: think about the structure (shape) of the enzyme and substrate.
The substrate must have a specific shape to fit into the specific shape of the active site in the enzyme (that catalyses the chemical reaction). Only specific enzymes and substrates fit together, which means a different enzyme is required to catalyse each different chemical reaction.
Explain the induced fit model of enzyme action by stating whether structural changes are required in the enzyme in order to bind the substrate.
In the induced fit model, the enzyme slightly changes the shape of its active site to accommodate the binding of a specific substrate in order to begin the chemical reaction.
Explain the lock and key model of enzyme action by stating whether structural changes are required in the enzyme in order to bind the substrate.
In the lock and key model, the shape of the enzyme’s active site is already complementary to the substrate. For this reason, no structural changes are required in the enzyme to allow the substrate to bind to the active site of the enzyme in order to begin the chemical reaction.
Where does a competitive inhibitor bind in order to prevent the substrate from binding to the enzyme’s active site?
A competitive inhibitor binds to the active site of the enzyme, as the competitive inhibitor has a complementary shape to the active site. The competitive inhibitor occupies the active site which prevents the substrate from binding to the active site.
Does the competitive inhibitor change the shape of the active site? If so what affect does this have on the function of the enzyme?
The competitive inhibitor does not change the shape of the enzyme’s active site but it does block the active site by occupying it, which prevents the chemical reaction from occurring.
Where does a non-competitive inhibitor bind in order to prevent the substrate from binding to the enzyme’s active site?
A non-competitive inhibitor binds to a regulatory binding site, which is separate from the active site. Once bound to the regulatory binding site, the shape of the enzyme’s active site changes, preventing the substrate from binding to the active site.
Does the non-competitive inhibitor change the shape of the active site? If so what affect does this have on the function of the enzyme?
The non-competitive inhibitor changes the shape of the enzyme’s active site by inducing conformational change within the protein, which occurs after the non-competitive inhibitor binds to the enzyme’s regulatory binding site. The change in shape of the enzyme’s active site means that the substrate no longer binds to the active site, which prevents the chemical reaction from occurring.
Where does a uncompetitive inhibitor bind in order to prevent the substrate from binding to the enzyme’s active site?
An uncompetitive inhibitor permanently binds to the enzyme’s active site via a covalent bond. Once the uncompetitive inhibitor is bound to the enzyme’s active site, it blocks the substrate from binding to the active site.
Does the uncompetitive inhibitor change the shape of the active site? If so what affect does this have on the function of the enzyme?
The uncompetitive inhibitor changes the shape of the enzyme’s active site by the inhibitor itself being permanently bound into part of the active site. As a result, the substrate cannot bind into the enzyme’s active site, which prevents the chemical reaction from occurring.
