Understand different models of enzyme function
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AP Biology › Understand different models of enzyme function
Which model of enzyme substrate binding posits that there is a transition state that develops before the reactants undergo change
Catalysis
Lock and key
Induced fit
Conformational change
Explanation
The lock and key model states that the active site of an enzyme precisely fits a specific substrate. The induced fit model states that the active site of an enzyme will undergo a conformational change when binding a substrate, to improve the fit.
The induced fit model better explains enzyme substrate binding than does the lock and key model. The induced fit model explains which of the following, that is not explained by the lock and key model
Broad specificity of enzymes
Narrow specificity of enzymes
Rigid structure of enzymes
Rigid structure of substrate
Explanation
The lock and key model states that the active site of an enzyme precisely fits a specific substrate. The induced fit model states that the active site of an enzyme will undergo a conformational change when binding a substrate, to improve the fit. The induced fit model accounts for the broad specificity of enzymes as the active site is not rigid, but can undergo a conformational change to better fit the substrate binding.
Which is NOT true of the lock and key model of enzyme substrate bonding?
The active site fits perfectly with the substrate
The active site is static
There is a transition state during which the shape of the active site changes to better fit the substrate
The enzyme does not have a separate catalytic group
Explanation
The lock and key model states that the active site of an enzyme precisely fits a specific substrate. The induced fit model states that the active site of an enzyme will undergo a conformational change when binding a substrate, to improve the fit. The induced fit model does not account for a transition state during which the shape of the active site changes to better fit the substrate.
The lock and key model of enzyme substrate binding posits that
The enzyme and substrate have complementary geometric shapes and are specific to one another
There is broad specificity of enzymes
Enzymes cannot be reused
The active site of the enzyme undergoes conformational change when the substrate binds
Explanation
The lock and key model states that the active site of an enzyme precisely fits a specific substrate. The induced fit model states that the active site of an enzyme will undergo a conformational change when binding a substrate, to improve the fit.
How do enzymes speed up a reaction?
Stabilization of transition state, lowering activation energy
Stabilization of transition state, increasing activation energy
Increase enthalpy of reaction
Decrease yield of reaction
Explanation
Enzymes speed up reactions through lowering the activation energy, of the energy needed to break bonds of reactants. The activation energy is lowered through stabilizing the transition state; the active site of the enzyme better fits the substrate, allowing bonds to more readily be broken, requiring less energy.
This model of enzyme and substrate interaction posits that the active site of the enzyme undergoes conformational change when the correct substrate binds
Lock and key model
Induced fit
Enzyme substrate model
Conformation model
Explanation
The lock and key model states that the active site of an enzyme precisely fits a specific substrate. The induced fit model states that the active site of an enzyme will undergo a conformational change when binding a substrate, to improve the fit.