Bioenergetics

Question 1

Entropy

Answer 1

The amount of randomness/disorder in a system. Always wish to increase (+delta S is FAVORABLE).
2nd law of thermodynamics.
To decrease entropy, energy must be put in

Question 2

Enthalpy

Answer 2

Measure of total energy of a thermodynamic system (heat or bond energy)
Change in H = products - reactants

Exothermic rxn: heat releases and is FAVORABLE, neg delta H
Endothermic rxn: heat required, unfavorable rxn.

Question 3

What is free energy?

Answer 3

Amount of energy in a system that can be converted into work at a given temp/pressure.
Delta G= H - T*deltaS

Question 4

Favorable?

Answer 4

Negative G
Negative H (enthalpy decreases)
Positive S (entropy increases)

Question 5

Thermodynamics laws

Answer 5

Energy conservation (cannot be created/destroyed), can change forms
Entropy is constantly increasing.

Question 6

High energy compound

Answer 6

Releases more than 6kcal/mol. 
2 classes:
1.) Thioester bonds (C-S, acetyl-coA)
2.) Phosphate bonds 
phophoanhydride (ATP), phosphocreatinine, phosphoenolpyruvate. 

Carbs and lipids give off lots of energy when combusted. Combustion of glucose occurs with positive S. Major way to harness energy for ATP.

Question 7

Redox rxn

Answer 7

LEO GR
oxidizing agent (accepts electrons, gets reduced. NAD+)
reducing agent (NADH, donates e)

Question 8

Forms of energy

Answer 8

kinetic and potential (chemical bonds, conc gradients etc.)

Question 9

Equilibrium constant and free energy?

Answer 9

Remember neg G is favorable.

If keq > 1, G is neg. and chemical rxn favors products (forward rxn).

Question 10

Spontaneous reaction?

Answer 10

Negative H, positive S (always spon.)
Neg H, neg S (pos at low temps)

G=h-T*s

Same sign means that it’s temp dependent.

Question 11

Free energy to redox potential?

Answer 11

G= -nF*E

Question 12

lots of Standard free energy changes are what?

Answer 12

ADDITIVE, so you can couple non-spontaneous and spontaneous rxns to make them favorable.