Electron carriers play a crucial role in biological processes, particularly in redox reactions, which are essential for cellular respiration. Two key electron carriers are NADH and FADH₂, both of which can transport a maximum of two electrons. These carriers function similarly to taxi cabs, shuttling electrons to various locations within a cell.

NADH is formed when the oxidized form, NAD⁺, picks up two electrons and a hydrogen ion, effectively becoming a "full taxi cab." Conversely, FADH₂ is created when FAD, in its oxidized state, captures two electrons and two hydrogen ions. This process can be remembered by noting that the presence of hydrogen in NADH and FADH₂ makes them "heavier," indicating they are in their reduced forms.

In the context of cellular respiration, the electrons carried by NADH and FADH₂ are delivered to the electron transport chain, which is the final stage of this metabolic pathway. This chain is critical for ATP production, as it utilizes the energy from these electrons to generate ATP, the energy currency of the cell.

Understanding the roles of NADH and FADH₂ as electron carriers is fundamental for grasping the intricacies of cellular respiration and energy production in living organisms. As you continue your studies, keep in mind how these carriers facilitate the transfer of electrons and contribute to the overall energy metabolism within cells.