Exam 2 Bioenergetics/Enzymes

Question 1

Who created GIbbs free energy?

Answer 1

Josiah Wilard Gibbs

Question 2

Free energy:

Answer 2

The energy that is avaiable to be used by a system

Question 3

Important* stuff to know: What do all chemical reactions involve?

Answer 3

all chemical reactions involve a change in the amount of free energy in the chemical system.

Question 4

Change in free energy:

Answer 4

The difference between the initial amount of free energy & the final amount of free energy G = Gf - Gi

Question 5

Spontaneous:

Answer 5

• Invert tendency
• Thermodynamically favorable
• exergonic reaciton
• Free energy lost

Question 6

Not spontaneous:

Answer 6

• No inherent tendency
• Not thermodynamically favorable
• Energy is put in
• Endergonic reaction

Question 7

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?

Answer 7

If delta G of a reaction is negative (spontaneous), then the delta G of the reverse rxn is positive (not spontaneous).

Question 8

Important points about delta G, the change in free energy of a reaction: #2 If delta G = 0 ?

Answer 8

If delta G = 0 then the chemical system is already in equilibrium and no net reaction is occurring.

Question 9

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?

Answer 9

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.

Question 10

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?

Answer 10

Delta G provides no information about the rates of a reaction.

Question 11

What does heat do to a reaction?

Answer 11

It allows for the reaction to be conducted if it cannot freely start.

Question 12

What does the subscript symbols designate?

Answer 12

It means that the variable is determined under standard conditions.

Question 13

What is the typical physiological conditions in the human skeletal muscle cells

Answer 13

37 degrees C

Question 14

What happens if a necessary biochemical reaction is not spontaneous:

Answer 14

a therm. unfavorable (not spontaneous) reaction can be driven by coupling it with a spontaneous (exergonic) reaction. (energy transfer).

Question 15

What is Delta G?

Answer 15

It is a state function, a macroscopic state variable

Question 16

What is a Enzymes?

Answer 16

• 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”

Question 17

Enzymes as a catalyst?

Answer 17

Is where enzymes emerge from the reactions unchanged, so they are recycled in the reaction, so only a small concentration of enzyme is sufficient.

Question 18

What are the 3 things enzymes do not do?

Answer 18

1. they do not change the equilibrium conditions of the reactions, don’t change the Keq of a reaction.
2. they do not change the delta G, do not change the endergonic into a exergonic reaction vice versa.
3. they do not supply energy to drive an endergonic reaction.

Question 19

What are globular enzymes?

Answer 19

Proteins

Question 20

what is a active site?

Answer 20

fold or grove

Question 21

What goes into the active site of the enzyme?

Answer 21

A prosthetic group, substrate (reactant)

Question 22

What is the substrate?

Answer 22

It is complementary to the shape of the active sight

Question 23

What does the prosthetic group do?

Answer 23

It helps to activate the enzyme group

Question 24

What are the two types of prosthetic groups?

Answer 24

Cofactor & Coenzyme

Question 25

What is a cofactor?

Answer 25

It is a small inorganic molecule or ion.

Question 26

What is a Coenzyme?

Answer 26

It is a organic molecule, for B vitamins, and Vit. C

Question 27

What does the enzyme substrate complex do?

Answer 27

It breaks down the substrate and releases the prosthetic group.

Question 28

What is enzyme kinetics?

Answer 28

It is the reaction rate as a function of enzyme concentration (assuming its a inexhaustible substrate)

Question 29

What happens to the reaction when the amount of enzyme is increased making the graph linear?

Answer 29

The reaction rate increases with the amount of enzyme used.

Question 30

What is the reaction rate going to be like if the substrate is increased, but the enzyme concentration is a constant?

Answer 30

The reaction rate asymptotically approaches the maximum reaction rate (Vmax) as [S] approaches infinity.

Question 31

What is enzyme activity?

Answer 31

It is where the environmental factors affect the shape of the enzyme protein therefore its function.

Question 32

How does the pH of a solution affect enzymes?

Answer 32

It can affect the optimum functions depending on the enzyme in use.

Question 33

What pH level are most enzymes having optimum function?

Answer 33

Near the neutral pH so around 7.

Question 34

What happens to the enzymes when there are changes in the pH?

Answer 34

The changes in pH can quickly alter the bonding patterns and reduce the functions of the enzyme.

Question 35

What are the stomach enzymes and what allows them to work in the low pH levels of your stomach?

Answer 35

The stomach enzymes are rennin and pespin, and they have adapted to the acid conditions.

Question 36

What affect does temperature have on enzymes?

Answer 36

With temp. the rxn rate increases exponentially with temp. increase, until the max rxn rate is reached at an optimum temp.

Question 37

What happens to the enzyme when the temperature goes beyond the max temp?

Answer 37

Going past the high temp limit leads to the denaturation of the protein.

Question 38

What are the four acts that can have an affect on the reaction rate of a reaction using enzymes?

Answer 38

- 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