Why are electron carriers such as NAD+ and FAD important?

Electron carriers like NAD+ and FAD play a crucial role in cellular respiration by facilitating the transfer of electrons during metabolic processes. When these carriers accept electrons (as NAD+ does to become NADH and FAD does to become FADH2), they store energy that can be released later.

These reduced forms, NADH and FADH2, then donate the high-energy electrons to the electron transport chain, a series of protein complexes located in the inner mitochondrial membrane. This transfer of electrons through the chain creates a proton gradient across the membrane, which is essential for ATP synthesis. As protons flow back into the mitochondrial matrix through ATP synthase, ATP is generated. This process is a key part of oxidative phosphorylation and contributes to the majority of ATP produced in cellular respiration.

Thus, the importance of electron carriers lies in their ability to link the products of earlier metabolic pathways, such as glycolysis and the Krebs cycle, to the final stage of ATP production, highlighting their essential role in energy metabolism.