The chemical process that occurs during cellular respiration is the breakdown of glucose to produce adenosine triphosphate (ATP). This process typically occurs in three main stages: glycolysis, the citric acid cycle, and oxidative phosphorylation. In glycolysis, glucose is broken down in the cytoplasm, generating a small amount of ATP and pyruvate. The citric acid cycle then produces electron carriers, which transfer electrons to the electron transport chain, where most ATP is generated through chemiosmosis, providing energy for cellular activities.