Question

Two pairs of electrons passing from NADH molecules to oxygen generate
A) 2 ATP
B) 3 ATP
C) 4 ATP
D) 6 ATP

Answer 1

Hint:Each NADH donates two electrons, and each $${\text{O}}_{\text{2}}$$ molecule must receive four electrons to produce water.

Complete answer:
Let’s discuss the given options and find the answer-
>Glycolysis begins with one molecule of glucose and ends with 2 pyruvates (pyruvic acid) molecules, a total of 4 ATP molecules, and 2 molecules of NADH. In the first half of the pathway, 2 ATP molecules are used to prepare the six-carbon ring for cleavage, and so the cell has a net gain of 2 ATP molecules and 2 NADH molecules for its use.
>NADH produces 3 ATP during the ECT or Electron Transport Chain with oxidative phosphorylation because NADH gives up its electron to Complex I. When Complex I transfer the electron to Complex III, energy is given off to pump protons across the membrane, creating a gradient. The electron moves again to the Complex IV and again pumps more electrons across the membrane. NADH starts with Complex I, it has more chances to pump more protons across the gradient, which powers the ATP synthase and gives us 3 ATP per molecule of NADH.
>Energy is needed from the starting of glycolysis to split the glucose molecule into 2 pyruvate molecules. These two molecules move to stage II of cellular respiration. The energy to split glucose is provided by 2 molecules of ATP. As glycolysis onsets, energy is released, and the energy is used to make 4 molecules of ATP.
>From ETS passage, electrons are responsible for the maintenance of the proton gradient which in turn takes part in the generation of ATP from the ATP synthase. The area of two pairs of electrons from NADH to oxygen will pump out 6 pairs of protons from the inner chamber of mitochondria. The backflow of six pairs of protons will produce 6 ATP.

Hence, option “D” 6 ATP is the correct answer.

Note: Electrons carried by $$\text{NADH}+{\text{H}}^{+}$$ and $$\text{FAD}{\text{H}}_{\text{2}}$$ are transferred to oxygen via a series of electron carriers, and ATPs are formed.