Question

In cellular respiration, a series of molecules forming an electron transport chain alternately accepts and then donates electrons. What is the advantage of such an electron transport chain? A scheme of cellular respiration. The initial compounds are 2H obtained from food via NADH and half of O2. 2H transforms into 2H plus and 2 electrons. These products have lower free energy than 2H and half of O2. Electrons lose their free energy in the electron transport chain. This energy is used for ATP synthesis. 2H plus and half of O2 lose their free energy and react with two electrons from the electron transport chain to create a water molecule that has less free energy than all the reactants. In cellular respiration, a series of molecules forming an electron transport chain alternately accepts and then donates electrons. What is the advantage of such an electron transport chain?

Answer 1

Release of electrons from reducing powers to O2 via four protein complexes allows release of small amount of energy at each step and makes the process energy efficient.

Step-by-step explanation:

If NADH and FADH2 would reduce O2 directly, a large amount of energy would have been released in a single step. On the other hand, oxidation of these reducing powers through a series of electron carrier release a small amount of energy at each step which in turn is temporarily stored in form of proton motive force across the inner mitochondrial membrane.

Transfer of a pair of the electron to O2 pumps four protons by complex I, four by complex III and two by complex IV. The resultant proton motive force effectively stores the energy of electron transfer. This energy is then used to drive ATP synthesis.