Cell Respiration

• Cell respiration occurs in the mitochondria.
• Oxygen breaks down glucose, a simple sugar, releasing energy.
• The energy is stored as ATP (adenosine triphosphate).
• Water and carbon dioxide are released as byproducts.
• Most of the energy needed by the cell comes from ATP.
• When quick energy is needed, the energy is used immediately.

In an average cell approximately 2 million ATP molecules are in use at one time.