Final answer:
The glycerophosphate shuttle transports electrons from cytosolic NADH to mitochondrial FADH2, resulting in the net gain of 1.5 ATP molecules per NADH molecule transferred, as opposed to 2.5 ATP via direct transfer.
Step-by-step explanation:
The glycerophosphate shuttle is involved in transferring electrons from NADH in the cytosol to FADH2 in the mitochondria. This shuttle system is vital as NADH cannot directly cross the mitochondrial membrane. The main objective of the glycerophosphate shuttle is to facilitate the transport of electrons from NADH across the mitochondrial membrane by converting dihydroxyacetone phosphate to glycerol-3-phosphate, which then donates electrons to FAD+ to form FADH2.
Due to the use of FAD+ instead of NAD+, this shuttle yields 1.5 ATP molecules per NADH molecule transferred versus the 2.5 ATP molecules produced when electrons are transferred by the malate-aspartate shuttle and directly by NADH in the electron transport chain. Thus, while it is efficient in ensuring the movement of electrons into the mitochondria, it is less energy-efficient than direct transfer methods. In the glycerophosphate shuttle, two NADH molecules produced in glycolysis will result in the net gain of three ATP molecules after their electrons have passed through the electron transport chain and oxidative phosphorylation.