Energy and Enzymes Flashcards
Enthalpy
H
the total energy of a system
Free energy
G
the usable amount of free energy in a system
Entropy
S
the amount of disorder
Equation that relates energy in a system
G = H -TS
What does T stand for?
Absolute temperature in kelvins
When is a reaction spontaneous?
when it is exergonic
there is a lowering of free energy in the system
What indicates a lowering of free energy?
negative delta G
How can T be manipulated to make a reaction spontaneous?
If H and S are both positive, T can be raised
If H and S are both negative, T can be lowered
Activation energy
the energy needed to reach the transition state of the reaction
What do enzymes do?
decrease the amount of activation energy
this speeds up the rate of the reaction
What are the three phases of enzyme activity?
- Initiation: reactants bind to the active site
- Transition state facilitation: the amount of activation energy needed is lowered
- Termination: the reactants are released
Competitive inhibition
Substrates cannot bind when a regulatory molecule binds to the ACTIVE SITE
What is competitive inhibition dependent on?
concentrations
Allosteric regulation
regulatory molecule binds to a different site on the enzyme besides the active site
allosteric regulation can activate or deactivate an enzyme
induces a shape change which makes the substate no longer able to bind
Induced fit model
a better understanding of the enzyme than the lock and key model
the enzyme changes shape in order to fit the substrate
