This animation shows how the proton gradient across the mitochondrial membrane powers the ATP synthase enzyme to make ATP. It is the third of three animations about cellular respiration. These animations bring to life the molecular engines inside mitochondria that generate ATP, the main source of chemically stored energy used throughout the body.
 
The electron transport chain (shown in the second animation) establishes a proton gradient across the inner mitochondrial membrane. ATP synthase uses the energy stored in the proton gradient to catalyze the synthesis of ATP. The molecular machinery involved in this process converts chemical energy to mechanical energy and provides a great example of the relationship between the structure and function of macromolecules.

The animation is appropriate for teaching advanced high school or college-level students the in-depth mechanisms of ATP synthesis. For more general audiences, the animation can be used as an example of molecular machines, enzymes, and chemical gradients in action. Depending on students’ background, it may be helpful to pause the animation at various points to discuss different reactions or molecules. 

All three cellular respiration animations are also available in a YouTube playlist.