Electron transport is a crucial process in cellular respiration and photosynthesis, where electrons are transferred through a series of proteins embedded in the mitochondrial or thylakoid membranes. This movement of electrons releases energy, which is used to pump protons across the membrane, creating a gradient. The energy stored in this gradient is then harnessed by ATP synthase to produce ATP, the primary energy currency of the cell. In photosynthesis, this process occurs in the light-dependent reactions, while in cellular respiration, it takes place during the oxidative phosphorylation stage.