Lecture 12: Redox potential

Question 1

What is the standard reduction or redox potential E0′

Answer 1

the measure of the tendency of a species to acquire the electrons in the redox reaction- therefore be reduced

Question 2

The free-energy change of a redox reaction can be readily calculated from what equation

Answer 2

ΔG’= -nFE’

Question 3

How are electrons from NADH and FADH2 used to reduce oxygen to water

Answer 3

The reaction of NADH/FADH2 losing its electron (+H) gives a positive E’ which makes a negative ΔG’. This coupled with the negative ΔG’ of reduction of O2 makes it very favourable reaction

Question 4

How is electron-transfer potential of NADH and FADH2 is converted to the phosphoryl-transfer potential of ATP

Answer 4

The making of ATP requires input of energy and this energy is given from the ΔG’ from reduction of O2 + the Oxidation of NADH/FADH2.

Question 5

What is the relationship between the size of E and the ΔG’

Answer 5

When E’ is positive (E’>0) then the ΔG’ is negative. This is spontaneous

When the E’ is negative (E’<0) then the ΔG’ is positive. This is unfavourable.