Bioenergetics And Oxidation Of Fuels: Overview

Front 1

Is a rxn that gives off heat spontaneous or nonspontaneous?

Back 1

spontaneous

Front 2

Can a rxn that obsorbs heat be spontaneous?

Back 2

yes

Front 3

What must the Gibbs free energy sign be to be spontaneous?

Back 3

Negative -∆G

Front 4

What is favorable, a postive or negative enthalpy change?

What is favorable, a positive or negative entropy change?

Back 4

negative

positive

Front 5

∆G= ? - ?

Back 5

∆G = ∆H - T∆S

Front 6

What does ∆H represent and which sign is favorable?

Back 6

heat absorbed or released
negative is favorable

Front 7

What does ∆S represent and which sign is favorable?

Back 7

measure of disorder
positve is favorable

Front 8

Which is thermodynamically favorable endergonic or exergonic?

Back 8

exergonic

Front 9

If ∆G is zero and a system is at equilibrium, can a change take place?

Back 9

No

Front 10

Can a rxn occur spontaneously if the ∆G is positive

Back 10

No, energy must be added

Front 11

∆G Products - ∆G Reactants = ?

Back 11

∆G of the rxn

Front 12

Given that the ∆G of a rxn depends only on the change in free energy of the products minus the reactants, does one take into account the intermediates?

Back 12

No, the mechanism is not important... just the start and end points

Front 13

Does ∆G tell us anything about the rate of a rxn?

Back 13

No

Front 14

Since ∆G does not reveal the rate of a rxn, what does?

Back 14

Concentration of reactants, products and the temperature

Front 15

So, how does nature vary the rate of a rxn?

Back 15

by varying the [product], [reactants]... NOT temperature

Front 16

What is the molar concentration of reactants and products, heat and pH at standard conditions (∆G°)?

Back 16

all of them are 1 moleK
T =298K
pH =7.0

Front 17

Can a rxn be thermodynamically favored at standard condition and be disfavored at physiological conditions?

Back 17

Yes and vice versa

Front 18

∆G = ∆G° + RT ln {([C][D])÷ (A][B])}, what is A and B and C and D, and which concentration will give you a thermodynamically favored rxn?

Back 18

C and D = products
A and B = reactants
high concentrations of reactants (denominator) will give a favorable rxn.

Front 19

if you start out with equal concentrations [reactant]= [product]and at equilibrium... then you end up with the following state the standard free energy: What is the ∆G?

a. [R]= [P]
b. [R]> [P]
c. [R]< [P]

Back 19

a. [R]= [P] ∆G° = zero
b. [R]> [P] ∆G° = positive
c. [R]< [P] ∆G° = negative

Front 20

A --> B + C ∆G = +5kcal/mol
B --> d ∆G = -8kcal/mol
A --> C + D ∆G = ? kcal/mol

1. Solve for the unkown.
2. How is this phenomenon exhibited in nature?

Back 20

1. ∆G = -3kcal/mol
2. Nature couples unfavorable reactions with favorable ones to drive the unfavorable one.

Front 21

What are the two ways nature manipulates the favorability of a rxn?

Back 21

1. Change product and substrate concentrations
2. Couple a thermodyamically unfavorable rxn to a favorable rxn to drive the unfavorable rxn.
.

Front 22

What is an example of coupling a thermodynamically unfavorable rxn to a favorable one?

Back 22

Increasing [ATP]:[ADP] when ATP is in abundance (unfavorable) by using a proton gradient (favorable)

Front 23

What is the free energy of the hydrolysis of ATP to ADP?

Back 23

∆G = -7.3 kcal/mol

Front 24

Why is it that the free energy of hydrolysis of ATP to ADP of as much as 12.7 Kcal/mol?

Back 24

Because of the overwhelming concentration difference,where [ATP]10X >[ADP], thus a lot of energy is needed to force the formation of ATP, so when it hydrolyzed it all free a lot of energy.

Front 25

Name 3 molecules, besides ATP, which have a high phosphoryl transfer potential (actually higher than ATP).

Back 25

Phosphoenolpyruvate
Creatine phosphate,
1,3-bisphosphoglycerate

Front 26

Why is the hydrolysis of ATP to ADP in the rxn of intracellular glucose (in the presence of ATP and Hexokinase) --> glucose-6-phosphate only -4 kcal/mol?

Back 26

Because it's couple to a disfavorable rxn (phosphorylating glucose is disfavorable).

Front 27

What effect does raising temperature have on a rxn?

Back 27

It raises the temperature of the reactants and the products with respect to the transition state, thus the heat changes the energy associated with the reactant and product and now the transition state is now relatively lower.

Front 28

How does nature lower the associated activation energy of a rxn?

Back 28

enzymes

Front 29

How do heat and enzymes differ in speeding up a rxn?

Back 29

heat changes the energy associated with reactants and products, while enzymes lowers the energy associated with the transitions state.

Front 30

What does a niacin deficiency cause? and why?

Back 30

Pelegra, which characterized by the 3Ds: dementia, dermatitis and diarrhea.

Why? Niacin is a precursor of NADH and NADPH.
.

Front 31

How do NAD+ and FAD get their 2 electrons? (reduced)

Back 31

The get them from the oxidation of molecules

Front 32

1) What is reduction potential a measure of?

2) In reduction potential, E, which is favorable positive or negative?

Back 32

1) Reduction potential is a measure of how much energy is released when a compound accepts an electron.

2) a positive reduction potential (+E) is favorable

Front 33

If a substance gives up electrons to H+, would the reduction potential be negative or positive?

Back 33

It would be negative

Front 34

If a substance has a lower affinity for electrons than H+, what would sign of the reduction potential be?

Back 34

negative

Front 35

For reduction potentials, which is favored positive or negative?

Back 35

Positive

Front 36

when summing up the reduction potentials, which do we reverse?

Back 36

The substance more likely to be oxidized... or the one with the lower electron affinity = more negative reduction potential.
.

Front 37

What is the relationship between free energy (∆G°') and reduction potential (∆E' sub zero)

Back 37

They are proportional

Front 38

Where are you more likely to find NADH and NADPH

Back 38

NADH in catabolic processes
NADPH in anabolic processes, e.g. synthesis of fatty acids.
.

Front 39

What is Coenzyme A?

Back 39

It is an activate carrier of an acyl groups, which can react with water by releasing lots of free energy

Front 40

What happen when you add water to acetyl-CoA group

Back 40

The Acetyl and CoA are hydrolyzed releasing free energy.

Front 41

Besides a CoA, what is an example of an activated carrier?

Back 41

ATP is an activated carrier of phosphoryl groups and pyrophosphoryl groups

Front 42

Which phosphoryl group is hydrolyzed when ATP --> ADP?

Back 42

the gamma (which is terminal) and the beta groups.

Front 43

What is the intermediate donor of free energy in biological systems, and in doing so is the deciding factor in whether reactions go forward or not?

Back 43

ATP

Front 44

What can shift the equilibria of coupled reactions by a factor of 10^8?

Back 44

ATP

Front 45

Name 5 biologicially important carriers of electrons.

Back 45

NAD, FAD, CoQ, various hemes, and various Fe-S complexes