Question

Why is it possible for electrons to flow from a redox center with a more positiveℰ°′ to one with a more negativeℰ°′ within an electron transfer complex?

Short answer

The microenvironment of the redox centre and the difference in the concentration of reactants and products may lead to reduction potential difference. This causes the electrons to flow from a redox centre with a more positive εº’ to more negative εº’ in a complex.

Step-by-step solution

Chemical and electrical gradient

The chemical gradient is the difference in solute concentration across a membrane. On the other hand, electrical gradient is the difference in charge across a membrane.

Cause of electrical gradient buildup

The active movement of electrons and protons across the cell membrane results in the formation of an electrical gradient. Protons are transferred out of the mitochondrion during electron transfer to create an electrochemical gradient whose free energy leads to ATP synthesis.

Flow of electron within a complex.

Depending on the microenvironment of the redox centre and the quantities of reactants and products, ℰ may differ from ℰ°′. As a result, electrons flow from a redox center with a more positive ℰ°′ to one with a more negative ℰ°′. Furthermore, the close coupling between subsequent electron transfers inside a complex may also pull electrons, resulting in a spontaneous event.