Oxidative Phosphorylation and ATP Generation

Oxidative phosphorylation is the process by which ATP is generated in the mitochondria of eukaryotic cells. It involves the transfer of electrons from NADH and FADH2 to oxygen through a series of electron carrier molecules in the electron transport chain (ETC). This process generates a proton gradient across the inner mitochondrial membrane, which is then used by ATP synthase to produce ATP.

Acetyl CoA and the Krebs Cycle

Acetyl CoA is an important molecule in cellular respiration. It is produced from the breakdown of glucose, fatty acids, and amino acids. Acetyl CoA enters the Krebs cycle (also known as the citric acid cycle or the tricarboxylic acid cycle) where it is oxidized to generate energy-rich molecules such as NADH and FADH2.

ATP Production from NADH and FADH2

NADH and FADH2 are electron carriers that are produced during the Krebs cycle. These molecules donate their electrons to the first complex of the electron transport chain, known as NADH dehydrogenase complex and succinate dehydrogenase complex respectively. The electrons then pass through a series of electron carriers, including cytochrome b-c1 complex, cytochrome c, and cytochrome oxidase.

Chemiosmosis and ATP Synthesis

As electrons pass through the electron transport chain, protons are pumped from the mitochondrial matrix to the intermembrane space, creating a proton gradient. This gradient drives the synthesis of ATP through a process called chemiosmosis. ATP synthase, located in the inner mitochondrial membrane, uses the energy from the proton gradient to phosphorylate ADP to ATP.

Calculating ATP Production

For every pair of electrons that pass through the electron transport chain, three ATP molecules are generated. NADH donates its electrons early in the electron transport chain, leading to the production of three ATP molecules. FADH2 donates its electrons later in the chain, resulting in the production of two ATP molecules.

Since two moles of acetyl CoA molecules are produced from one mole of glucose during cellular respiration, the total number of ATP molecules generated from the complete oxidative phosphorylation of two moles of acetyl CoA is:

(2 moles acetyl CoA) x (3 ATP/mole NADH) + (2 moles acetyl CoA) x (2 ATP/mole FADH2) = 6 ATP + 4 ATP = 10 ATP

Therefore, the correct answer is 10 ATP.