How is the electron transport chain primarily defined?

The electron transport chain is primarily defined as a sequence of proteins transferring electrons. This series of protein complexes, located within the inner mitochondrial membrane in eukaryotes, plays a crucial role in cellular respiration.

During this process, electrons are transferred through the chain from electron donors such as NADH and FADH2 to acceptors like oxygen. This transfer occurs through a series of redox reactions, where electrons lose energy at each step. The energy released during these transfers is used to pump protons across the membrane, creating a proton gradient that ultimately drives the synthesis of ATP through ATP synthase.

This definition is fundamental to understanding cellular respiration, as the electron transport chain is a key step in oxidative phosphorylation, where most of the ATP produced during respiration is generated. The focus on the protein sequence emphasizes how the structural arrangement and interactions of these proteins are vital for the efficient transfer of electrons and energy production within the cell.