Here's how it works:
* Proton Gradient: During cellular respiration (specifically in the electron transport chain), electrons are passed from molecule to molecule, releasing energy. This energy is used to pump protons (H+) across the inner mitochondrial membrane, creating a concentration gradient.
* ATP Synthase: ATP synthase is embedded in the inner mitochondrial membrane. It has two main parts:
* F0 unit: This acts as a channel through which protons flow back down their concentration gradient from the intermembrane space to the mitochondrial matrix.
* F1 unit: This is where ATP is actually synthesized. The flow of protons through F0 rotates a part of F1, which changes its conformation and allows it to bind ADP and inorganic phosphate (Pi) to form ATP.
In summary: ATP synthase harnesses the potential energy stored in the proton gradient to drive the synthesis of ATP. This process is known as chemiosmosis.
