Bioenergetics/Metabolic Pathways Flashcards
Standard state requirements
1M reactants, 1M products, 1ATM for gases, 25 degrees C
Difference between G0 and G0’
Prime is the biochemical standard state where we have the reaction done in water at 55.5M and at neutral pH of 7.0
Negative delta G
Spontaneous Reaction (the amount of energy available to do work is higher in the products)
Positive delta G
Non-spontaneous
Delta G0 equation
= - 1.36log ([P]/[R])
= -RT log ([P]/[R])
The standard free energy change for a reaction is related to the equilibrium constant of the reaction
Delta G equation
Delta G = Delta G0 + 1.36log ([P]/[R])
The “real” amount of energy available to a cell is related to the standard gibbs free energy and the equilibirum constant
Delta G formula in terms of RT and ln
DeltaG = RTln([P]/[R]) - RTln([Peq]/[Req])
DeltaG0 in terms of RT and ln
DeltaG0 = - RTln([Peq]/[Req])
How do we determine the oxidation number of a carbon?
For every bond to H, subtract 2
For every single bond to O, N, S, or a halogen, add 1 [think SON Halogen]
Double bonds add 2
Triple bonds add 3
For every bond to another C, add 0.
What formula do we use to find the Delta G0’ in calories
Delta G0’ = -nF(Delta)E0’
n = number of electron equivalents transferred in the reaction
F = 23.06 kcal/volt/equivalent of electrons (Faraday constant)
Number of ATP per NADH
2.5/NADH
Number of ATP per FADH2
1.5ATP/FADH2
Why are ATP bonds high energy bonds?
Because they are between two negative phosphate groups which repel each other putting strain on the bond
How do we get the energy from ATP?
You cannot just capture the exothermic heat caused by the hydrolysis reaction. You instead need to transfer the phosphates to carrier transfer metabolites or proteins (phosphoryl transfer reaction)
S
Entropy
H
Enthalpy
P
High energy phosphate bond
First law of thermodynamics
Conservation of energy - Energy in a system is always constant
Second law of thermodynamics
Entropy is always increasing - We favor disorder
Kelvins
Celsius + 273
Types of work we can do with energy from ATP
- Mechanical Work
- Transport Work (Active Transport)
- Biochemical Work
Mechanical work
High energy phosphate group generates movement by changing the conformation of a protein
Example: ATP bound to myosin ATPase in muscle fibers is hydrolyzed, causing the myosin conformation to turn to a “cocked” position, ready to associate with the actin filament
Transport Work
This is also called active transport
Phosphates from the ATP used to act on the proteins in the plama membrane to cause a conformational change in the protein possibly pushing things against their concentration gradients
Biochemical work
Energy-requiring reactions that use ATP and the bond energy to cause chemical reactions such as with detoxification of drugs
What do all metabolic pathways have in common?
A negative gibbs free energy
Unfavorable reactions are coupled with favorable ones
Creatine Phosphate
Has a high energy phosphate group (~-10 kcal/mol)
Amount of creatine in urine is a good determinant of muscle mass. Creatine in plasma is indicitive of kidney failure.
Oxidation versus Reduction
LEO the lion says GER
(loss of electrons = oxidation)
(gain of electrons = reduction)
The most energetic compounds are also the most?
Reduced
H2
Hydrogen molecule
Two protons with two electrons
H.
Hydrogen atom
one proton with one electron
H-
Hydrogen ion
One proton with two electrons
What does NAD+ accept?
H- and is reduced to NADH
(aka two electrons)
What does FAD accept?
2H. and is reduced to FADH2
(also carries 2 electrons)
FADH2 is derived from what?
Riboflavin (Vitamin B2)
NADH is derived from what?
Niacin (Vitamin B3)
What happens when the [NADH]/[NAD+] ratio is high?
The production of lactic acid via hydrogenation using NADH
What happens under aerobic conditions to FADH2 and NADH
They are re-oxidized in the mitochondria to NAD+ and FAD
Why do we get more ATP production per NADH than we get from FADH2
Because NADH is a stronger reducing agent
