Bioenergetics Flashcards
Entropy
randomness associated with a given system
∆S = + , favorable, disorder increases in a system
∆S = - , unfavorable, disorder decreases in a system
Enthalpy
measure of heat content of a system
Exothermic reaction vs. endothermic raction
Exothermic = ∆H (-), release heat, favorable Endothermic = ∆H (+) absorb heat, unfavorable
Gibbs Free Energy (G)
Amount of thermodynamic energy in a system that can be converted into work at a given temperature and pressure
High energy compounds
compounds with bonds that release greater than 7 kcal/mol of energy when broken (∆G= -7)
Oxidation-reduction reaction
A chemical reaction involving the transfer of electrons away from one compound (oxidized compound, e- donor) to another compound (reduced compound, e- acceptor)
First Law of Thermodynamics
Energy conservation:
-cannot be created or destroyed, only converted
Second Law of Thermodynamics
The entropy of the universe is constantly increasing
4 kinds of kinetic energy
kinetic = energy of motion
1) radiant
2) thermal
3) mechanical
4) electric
4 kinds of potential energy
potential = stored energy
1) stored in chemical bonds
2) stored in concentration gradients
3) stored in electric fields from charge separation
4) stored in redox pairs
Radiant energy
carried in photons from the sun
Electric energy
Energy movement of charged particles down gradients of electric potential
3 Equations we have to memorize about Gibbs Free Energy
1) ∆G = ∆H - T∆S
(T in KELVIN)
2) ∆G = -nF∆E
(n=#electrons transferred), (F=Faraday constant), (∆E=difference in reduction potential in VOLTS)
3) ∆G = ∆Go + (RT) (ln [products]/[reactants]
(R=gas constant) (∆Go=free energy under standard conditions)
4) ∆Go = (-RT) ln (Keq)
∆G 0 =
∆G = 0 =
∆G 0 = not spontaneous
∆G = 0 = at equilibrium
∆E = ?
Eo electron acceptor - Eo electron donor
Activation energy
- Energy barrier between products and reactants
- determines RATE of reaction, is acted upon by enzymes
High (+) Eo means…
molecule is more electronegative (loves to accept electrons)
Low (-) Eo means…
molecule is electropositive (gives away electrons)
As electrons pass from compounds with _____ to _______ E free energy is _________
low to high E
Free energy is RELEASED (-)
Electron Flow
movement of electrons through a series proteins (cytochromes, co-factors) that are alternately oxidized and reduced releases energy in small steps that is used to make high energy compounds (ATP, NADH, and NADPH) that are used to do biological work
_____ is the final electron acceptor from the metabolism of glucose
Oxygen (O2)
NADH
Stores potential energy
ATP is made by…
- harnessing the energy gradient of H+ concentration and electrical potential across the inner membrane of the mitochondria
- High [H+] outside, because H+ pumped out of matrix
Two classes of high energy bonds
- Thioester bonds C-S
2. Hi energy phosphate bonds
Acetyl CoA
- Used as a source of energy in cells
- Cleavage of thioester bond (C-S) results in an oxygen-ester stabilized by resonance
Types of high energy phosphate bonds (3)
1) Phosphoanhydride bonds P-O-P (ATP)
2) Phosphocreatine bonds P-N
3) Phosphoenolpyruvate C-O-P
Loss of electrons is _______
Gain of electrons is ______
oxidation
reduction
