The cytochromes are heme containing proteins that function as electron carriers

Question

The cytochromes are heme containing proteins that function as electron carriers in the mitochondria Calculate the difference in the reduction potential (Delta Edegrees prime) and the change in the standard free energy (Delta Gdegrees prime) when the electron flow is from the carrier with the lower reduction potential to the higher. cytochrome c_1 (Fe^3+ ) + e^minus rlhar cytochrome c_1 (Fe^2+ ) Edegrees prime = 0.22V cytochrome c_1 (Fe^3+ ) + e^minus rlhar cytochrome c_1 (Fe^2+ ) Edegrees prime = 0.254V Calculate Delta Edegrees prime Delta Edegrees prime = Calculate Delta Edegrees prime Delta Edegrees prime =

Explanation / Answer

The reactions will be:

cytochrome c1(Fe+2) <----> cytochrome c1(Fe+3) +e-

cytochrome c(Fe+3) + e- <----> cytochrome c(Fe+2) +e-

The first reaction is the opposite of the one given because the electrons must be formed by the reaction with lower reduction potential in order to move to the one with higher potential.

DE0´= E0 cathode - E0 anode= 0.254-0.22= 0.034V

DG0´= -nFDE0´

n=number of electrons exchanged, in this case 1

F= Faraday constant

DG0´= -1 x 96485 x 0.034= -3280.49 J/mol = 3.28 kJ/mol

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