Question

Why do your cells utilize an electron transport chain to harness the energy of NADH oxidation to make ATP rather than oxidizing NADH directly to make ATP? Discuss TWO reasons.

Answer 1

1) There needs to be a mechanism for harnessing the released energy. Normally oxidative energy is lost as heat. The whole purpose of using the electron transport chain is to use the oxidation of a single molecule of NADH to produce 3 ATP. Even if the NADH is oxidized, there must exist some way of capturing that energy. The ETC by exploiting complexes that pass the electron as donors and acceptors down a gradient 4 times generate 3 ATP. A much higher portion of the energy released during oxidation is harnessed as ATP. There are three respiration phases that are present. The ETC is the most efficient. ETC produces 34 ATP per molecule of glucose, citric acid cycle only produces 2.

2. Moreover, NAD and FAD are required again for the citric acid cycle. Complex 1 and two produce NAD and FAD to be reintroduced into the citric acid cycle.