What is the role of NADH and FADH2 produced in the Citric Acid Cycle?

The role of NADH and FADH2 produced in the Citric Acid Cycle is primarily to carry electrons to the electron transport chain. During the cycle, various reactions lead to the reduction of NAD+ to NADH and FAD to FADH2. These reduced coenzymes serve as crucial electron carriers that transport electrons to the electron transport chain, which is located in the inner mitochondrial membrane.

Once there, the electrons from NADH and FADH2 are passed along a series of proteins (complexes) in the chain, which ultimately leads to the production of ATP through oxidative phosphorylation. The energy released during the electron transfer processes drives the pumping of protons across the inner mitochondrial membrane, creating a proton gradient that is utilized by ATP synthase to generate ATP from ADP and inorganic phosphate.

This role is critical for cellular respiration, as the electrons derived from NADH and FADH2 contribute significantly to the overall energy yield of glucose metabolism. The final pathway in which ATP is generated from the reduced cofactors through the electron transport chain is fundamental to the energy economy of the cell.