The Basics of Energy Metabolism Flashcards
The metabolism of all living cells is an (open or closed) system?
open
What is the universal molecular carrier for biological energy?
ATP/ADP
Is the cell at equilibrium?
No, it is at a steady state and is specifically held out of equilibrium
What is Keq
the equilibrium constant of a reaction
What is ∆G0’?
The change in Gibbs free energy for a reaction under STANDARD conditions
What are the standard conditions?
naught = 1M initial products and reactants
prime = pH7
What’s the formula for ∆G0’?
∆G0’ = -R x T x ln(Keq)
What are the R and T in the ∆G0’ equation?
R = 8.32
T = 25C (298K)
RT = 2.48 kJ/mol
What’s the formula for Keq?
[products] / [reactants]
Keq > 1
products favored and exergonic (releases energy)
Keq < 1
reactants favored and endergonic (requires energy)
∆G0’ > 0
reactants favored and endergonic (requires energy)
∆G0’ < 0
products favored and exergonic (releases energy)
The Keq of ATP/ADP is what and means what?
Keq = 2.7 x 10^-6
At equilibrium there’s more ADP than ATP
What is the ∆G0’ of ATP/ADP and what does it mean?
∆G0’ = 31.8 kJ/mol
ADP (reactant) is favored and the reaction is endergonic (requires energy)
What is ∆G’?
The change in Gibbs free energy for a reaction under NON STANDARD conditions
What is the equation for ∆G’?
∆G’ = ∆G0’ + (R x T x ln ([products] / [reactants])
∆G’ > 0
reactants favored and endergonic (requires energy)
∆G’ < 0
products favored and exergonic (releases energy)
How do you find the actual [ATP] and [ADP]?
metabolics
What’s [ATP] for E. coli?
9.6 x 10^-3 M
What’s [ADP] for E. coli?
0.56 x 10^-3 M
What’s [PO4^3-] for E. coli?
1 x 10^-3 M
What’s the ∆G’ of E. coli for ATP synthesis and what does it mean?
56 kJ/mol
ADP (reactant) is favored and endergonic (requires energy, specifically 56kJ/mol to make ATP)
Which do you expect to be larger during ATP synthesis: ∆G0’ or ∆G’?
∆G’
because ∆G’ = ∆G0’ + (RT x ln ([products] / [reactants])) and the [products] / [reactants] is > 1
The electron acceptor is the (oxidant or reductant)?
oxidant
The electron donor is the (oxidant or reductant)?
reductant
Reduction (gains or loses) electrons?
Reduction Is Gain (RIG)
Oxidation (gains or loses) electrons?
Oxidation Is Loss (OIL)
NADPH is an electron (donor or acceptor)?
electron donor
NADP+ is an electron (donor or acceptor)?
electron acceptor
NADH is an electron (donor or acceptor)?
electron donor
NAD+ is an electron (donor or acceptor)?
electron acceptor
Reduction potential
measurement of how easily a molecule can take up electrons
oxidation potential
measurement of how easily a molecule can give up electrons
A hydride = what?
1 H- = 1 (H+) + 2 e-
[H] = what?
1 (H+) + 1 e-
What is the equation for ∆G0’ ?
∆G0’ = -n x F x ∆E0’
n = number of e-
F = 97 kJ / V
∆E0’ = standard reduction potential
What is ∆E0’?
the STANDARD reduction potential
(E0’ of e- acceptor) - (E0’ of e- donor)
∆E0’ < 0
more likely to give up e- (mainly oxidized)
∆E0’ > 0
more likely to keep e- (mainly reduced)
What does NAD stand for?
Nicotinamide Adenine Dinucleotide
What does NAD do?
hydride transfer (H- = 2 e- + H+)
What is the structure of NAD+ and NADP+?
What is the structure of NADH and NADPH?
What’s the structure equation for NAD(P)+ to NAD(P)H?
What’s the oxidation half reaction of NAD(P)+/NAD(P)H?
NAD(P)H -> NAD(P)+ + (H-)
What’s the reduction half reaction of NAD(P)+/NAD(P)H?
NAD(P)+ + (H-) -> NAD(P)H
What’s the E0’ of NAD(P)+ / NAD(P)H and what does it mean?
-0.32 V
NAD(P)H wants to give up e-
What is ∆G0’ of NAD(P)+ / NAD(P)H and what does it mean?
∆G0’ = 0
because both NAD(P)+ (e- acceptor) and NAD(P)H (e- donor) have a E0’ = -0.32 so ∆E0’ = 0 which makes the entire formula = 0
neither the product or reactant are favored
What’s non-standard conditions?
pH 7 and 25 C (298 K) but [actual]
What’s ∆E’?
the reduction potential under NON-STANDARD conditions (actual conditions)
What’s the E’ of NADP+ / NADPH and what does it mean?
E’ = -0.373 V
NADPH wants to give up e-
What’s the ratio of NADH / NAD+?
1/31
(ln this)
What’s the ratio of NADP+ / NADPH?
57/1
(ln this)
What’s the E’ of NAD+ / NADH and what does it mean?
E’ = -0.275 V
NADH wants to give up e-
What is the formula for E’?
E’ = E0’ - ( (RT/nF) x ln( [red] / [ox]) )
The transfer of a hydride from NADPH to NAD+ is (exergonic or endergonic)?
exergonic
What’s the ∆G’ of NADPH to NAD+ and what does it mean?
∆G’ = -19 kJ/mol
NAD+ is favored and is exergonic (releases energy)
