Chapter 11 ICP

"Redox Tower"

Electrons donated by the “half-reactions” on top can be consumed in a half-reaction lower on the tower to complete a thermodynamically favorable reaction. Since the oxidation of glucose lies at the top of the tower and the reduction of NAD+ is below it, this electron flow is thermodynamically favorable. We can see that this is favorable to generate ATP (bottom).

Standard Reduction Potential

Use the table to (A) write out the balanced reaction between NADH and water and (B) to compute the standard reduction potential for it.

Answer

1/2O₂ + 2H⁺ + 2e' → H₂O; e^0' = 0.816 volts

NAD⁺ + 2H⁺ + 2e' → NADH + H⁺ ; e^0' = -0.320 volts

Δe^0' = e^0'(what gets reduced) - e^0'(what gets oxidized)

Δe^0' = 0.816 - (-0.320) = +1.14 volts

Equivalent to approximately -220 kJ/mol and can drive the formation of several ATP molecules.