Answer:
The electron transport chain (ETC) is located in the mitochodrial cristae. As electrons move from one protein complex to the other via redox reaction, energy is used to pump hydrogen ions (H+) from the matrix to the intermembrane space of the mitochondria. As hydrogen ions flow down the concentration gradient from the intermembrane space to the mitochodrial matrix, ATP is synthesized by the enzyme ATP synthase.
The ATP synthase complex can be compared to the gates of a dam. when the gates of a hydroelectric dam are opened, water rushes through, and electricity (energy) is produced. Similarly, when H+ ions flow down a gradient from intermembrane space into the matrix, the enzyme ATP synthase synthesizes ATP from ADP and inorganic phosphate or P<em>i. </em>This process is called chemiosmosis because ATP production is linked with the establishment of a proton (H+) gradient across the membranes.
