What is the primary role of NADH and FADH2 in cellular respiration?

The primary role of NADH and FADH2 in cellular respiration is as electron carriers. During the metabolic pathways of cellular respiration, such as glycolysis, the citric acid cycle, and oxidative phosphorylation, these molecules play a crucial role in transferring electrons from substrates to the electron transport chain.

NADH, which is derived from NAD+, and FADH2, which comes from FAD, are formed during the oxidation of fuel molecules, capturing high-energy electrons released during the breakdown of glucose and other nutrients. By carrying these electrons to the electron transport chain, they facilitate the production of ATP via oxidative phosphorylation. The energy released from the transfer of electrons through the chain is used to pump protons across the mitochondrial membrane, creating a gradient that ultimately drives ATP synthesis through ATP synthase.

This function of electron transport is vital to cellular respiration, as it enables the efficient extraction of energy from nutrients. Without NADH and FADH2 acting effectively as electron carriers, the entire process of aerobic respiration would not be able to occur, resulting in reduced ATP production and energy availability for the cell.