Exam 2 Bioenergetics/Enzymes Flashcards
Who created GIbbs free energy?
Josiah Wilard Gibbs
Free energy:
The energy that is avaiable to be used by a system
Important* stuff to know: What do all chemical reactions involve?
all chemical reactions involve a change in the amount of free energy in the chemical system.
Change in free energy:
The difference between the initial amount of free energy & the final amount of free energy G = Gf - Gi
Spontaneous:
- Invert tendency
- Thermodynamically favorable
- exergonic reaciton
- Free energy lost
Not spontaneous:
- No inherent tendency
- Not thermodynamically favorable
- Energy is put in
- Endergonic reaction
Important points about delta G, the change in free energy of a reaction: #1 If delta G of the reaction is spontaneous then what is the delta G of the reverse reaction?
If delta G of a reaction is negative (spontaneous), then the delta G of the reverse rxn is positive (not spontaneous).
Important points about delta G, the change in free energy of a reaction: #2 If delta G = 0 ?
If delta G = 0 then the chemical system is already in equilibrium and no net reaction is occurring.
Important points about delta G, the change in free energy of a reaction: #3 What does the total free energy change of the pathway depend on?
Total free energy change of a pathway depends only on the difference btw the initial Gi & the final Gf energy levels, & not on the path taken.
Important points about delta G, the change in free energy of a reaction: #4 Does delta G give information about the rates of a reaction?
Delta G provides no information about the rates of a reaction.
What does heat do to a reaction?
It allows for the reaction to be conducted if it cannot freely start.
What does the subscript symbols designate?
It means that the variable is determined under standard conditions.
What is the typical physiological conditions in the human skeletal muscle cells
37 degrees C
What happens if a necessary biochemical reaction is not spontaneous:
a therm. unfavorable (not spontaneous) reaction can be driven by coupling it with a spontaneous (exergonic) reaction. (energy transfer).
What is Delta G?
It is a state function, a macroscopic state variable
What is a Enzymes?
- its a catalysts of biochemical reactions
- It increases the rate of biochemical reactions
- enzymes are unique to a given reaction in most cases, “one enzyme - one substrate”
Enzymes as a catalyst?
Is where enzymes emerge from the reactions unchanged, so they are recycled in the reaction, so only a small concentration of enzyme is sufficient.
What are the 3 things enzymes do not do?
- they do not change the equilibrium conditions of the reactions, don’t change the Keq of a reaction.
- they do not change the delta G, do not change the endergonic into a exergonic reaction vice versa.
- they do not supply energy to drive an endergonic reaction.
What are globular enzymes?
Proteins
what is a active site?
fold or grove
What goes into the active site of the enzyme?
A prosthetic group, substrate (reactant)
What is the substrate?
It is complementary to the shape of the active sight
What does the prosthetic group do?
It helps to activate the enzyme group
What are the two types of prosthetic groups?
Cofactor & Coenzyme
What is a cofactor?
It is a small inorganic molecule or ion.
What is a Coenzyme?
It is a organic molecule, for B vitamins, and Vit. C
What does the enzyme substrate complex do?
It breaks down the substrate and releases the prosthetic group.
What is enzyme kinetics?
It is the reaction rate as a function of enzyme concentration (assuming its a inexhaustible substrate)
What happens to the reaction when the amount of enzyme is increased making the graph linear?
The reaction rate increases with the amount of enzyme used.
What is the reaction rate going to be like if the substrate is increased, but the enzyme concentration is a constant?
The reaction rate asymptotically approaches the maximum reaction rate (Vmax) as [S] approaches infinity.
What is enzyme activity?
It is where the environmental factors affect the shape of the enzyme protein therefore its function.
How does the pH of a solution affect enzymes?
It can affect the optimum functions depending on the enzyme in use.
What pH level are most enzymes having optimum function?
Near the neutral pH so around 7.
What happens to the enzymes when there are changes in the pH?
The changes in pH can quickly alter the bonding patterns and reduce the functions of the enzyme.
What are the stomach enzymes and what allows them to work in the low pH levels of your stomach?
The stomach enzymes are rennin and pespin, and they have adapted to the acid conditions.
What affect does temperature have on enzymes?
With temp. the rxn rate increases exponentially with temp. increase, until the max rxn rate is reached at an optimum temp.
What happens to the enzyme when the temperature goes beyond the max temp?
Going past the high temp limit leads to the denaturation of the protein.
What are the four acts that can have an affect on the reaction rate of a reaction using enzymes?
- increasing the amount of enzyme
- with the increase of substrate will mean the decrease in the amount of affect on a enzyme that is constant.
- pH can affect the functions allowed for the enzyme
- Temperature can increase the reaction rate of the enzyme until a certain point, to much it could degrade the protein
