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Aerobic respiration takes place in an organelle called a mitochondrion. Remember: “one mitochondrion”, “many mitochondria”. Glucose and oxygen are involved in a series of chemical processes and eventually, carbon dioxide and water are released. In the process, energy is released in the form of ATP: adenosine triphosphate.

Glucose + Oxygen → Carbon Dioxide + Water

When we do exercise, we often can’t get enough oxygen. Even breathing faster and more deeply isn’t enough. In this case glucose alone is converted into lactic acid, and a small amount of energy is release.

Glucose → Lactic Acid.