Exam 2

Question 1

Free Energy

Answer 1

The energy that is available to be used by a system

Question 2

Change in Free Energy

Answer 2

The difference between the initial amount of free energy and the final amount of free energy. (delta) G = Gf - Gi

Question 3

Reactants

Answer 3

The initial state of the chemical system initial free energy (Gi)

Question 4

Products

Answer 4

The final state of the chemical system (Gf)

Question 5

Spontaneous

Answer 5

Inherent tendency for a process to go in a particular direction

Question 6

Spontaneous (exergonic reaction)

Answer 6

Inherent tendency the thermodynamically favorable

Question 7

Not spontaneous (endergonic reaction)

Answer 7

No inherent tendency - Not thermodynamically favorable

Question 8

Spontaneous (delta G)

Answer 8

the answer should be negative

Question 9

Not spontaneous (delta G)

Answer 9

the answer should be positive

Question 10

Keq (equation)

Answer 10

[products] / [reactants]
(under physiological conditions, delta G > 0)

Question 11

Keq^prime (equation)

Answer 11

[products] / [reactants]
(under standard conditions)

Question 12

delta G (equation)

Answer 12

delta G^prime + RTlnkeq
(R = 1.987x10^-3Kcalmol^-1K^-1)
(T = 310 K)

Question 13

delta G^prime (equation)

Answer 13

-(R)(T)^prime(ln(keq^prime))
(R = 1.987x10^-3Kcalmol^-1K^-1)
(T = 298 K)

Question 14

What enzymes are and what they do

Answer 14

1. Increase the rate of biochemical reactions by reducing the energy of activation, Ea.
2. Enzymes are unique to a given reaction in most cases, “one enzyme - one substrate.”
3. As catalysts, enzymes emerge from the reaction unchanged, so they are recycled in the reaction, so only a small [E] is sufficient.

Question 15

What enzymes DO NOT DO

Answer 15

1. Do not change the equilibrium conditions, do not change keq of a reaction.
2. Do not change delta G, and do not change endergonic into exergonic reaction.
3. Do not supply energy to drive an endergonic reaction.

Question 16

Enzymes are

Answer 16

They are globular proteins

Question 17

Two types of the prosthetic groups

Answer 17

1. Cofactor: small, inorganic molecule or ion.
2. Coenzyme: organic molecules B vitamins and vitamin C

Question 18

Enzymes

Answer 18

Catalysts of biochemical reactions

Question 19

Important points about delta G

Answer 19

1. Reversible, same amount:
   A -> B, delta G = -5Kcalmol^-1K^-1 (exergonic)
   B -> A, delta G = +5Kcalmol^-1K^-1 (endergonic)
2. If delta G = 0, then the system is at equilibrium, and no net reaction is occurring.
3. The total free energy change of a pathway depends only on the difference between the initial Gi and the final Gf and not on the path taken: A -> B -> C -> D.

Question 20

Ea (energy of activation)

Answer 20

“energy barrier” measure of stability

Question 21

Prosthetic group

Answer 21

helps to activate the enzyme

Question 22

Active site

Answer 22

folder groove

Question 23

Enzyme activity

Answer 23

Environmental factors affect the shape of the enzyme protein, therefore its function

Question 24

pH of solution (graph)

Answer 24

• stomach enzymes (pepsin, rennin) adapted to acid conditions (more towards pH = 1)
• most enzymes have optimum function near neutral pH
• changes in pH can quickly alter bonding patterns and reduce function of enzyme

Question 25

Temperature (graph)

Answer 25

• reaction rate increases exponentially with temperature…
• … until a maximum rate is reached at an optimum temperature…
• … above which high temperatures lead to the denaturation of the protein.