Lecture 7. Energy and Metabolism Flashcards
Standard free energy equation
ΔG = ΔG°’ + RTlnq
R
Gas constant
T
Absolute temperature in Kelvin
q
Mass action ratio
ΔG°’
Standard free energy at pH 7, 25°C and 1 atm
What does q = at equilibrium?
Keq
What does Keq equal at equilibrium?
Keq = e^-ΔG°’/2.5
What can relatively small changes in ΔG°’ lead to in Keq?
Big changes
What is the main energy carrier in the cell?
ATP
What is Pi?
Inorganic phosphate
What is PPi?
Pyrophosphate
What can Keq be affected by?
Coupling reactions
What happens in oxidation?
A compound donates electrons
What happens in reduction?
A compound accepts electrons
What does a strong oxidising agent want to do?
Accept electrons - O₂
What do strong reducing agents do?
Readily donate electrons - NADH
What are good reductants?
Give of electrons even when there’s many around
What are good oxidants?
Take up e⁻ even when only a few around
What equation links redox potentials to ΔG°’?
ΔG°’ = -nFΔE°’
n
Number of electrons
F
Faraday constant
What does a positive ΔE°’ give?
A negative ΔG°’
What is ΔE°’?
Overall voltage of a redox reaction
