Question

Cytochrome c is a mobile carrier of electrons between ______________.

• A. complex I and complex II
• B. complex II and complex III
• C. complex III and complex IV
• D. complex I and complex IV

Answer 1

The correct option is C complex III and complex IV

Cytochrome c is a mobile carrier of electrons attached on the outer side of the inner mitochondrial membrane. It transfers the electrons between complex III and complex IV.

During glycolysis and citric acid cycle, $NADH+H^{+}$ and $FAD{H}_2$ are formed. These get oxidised and release electrons that pass through the various electron acceptors of the electron transport chain. Electrons released from $NADH+H^{+}$ are initially transferred to complex I. From complex I, electrons are transferred to ubiquinone, a mobile carrier of electrons. Ubiquinone also receives electrons from $FAD{H}_2$ through complex II. Ubiquinone transfers electrons to complex III. Cytochrome c transfers electrons from complex III to complex IV. From complex IV, oxygen accepts electrons. Oxygen is the final acceptor of the electrons and also picks up $H^{+}$ to form water.