ATP stores some of the energy from glucose molecules during glycolysis. How is the remaining energy from these glucose molecules released?
Water
Electron Transport Chain
Heat
Carbon Dioxide
The remaining energy from glucose molecules is released through two main processes: the electron transport chain and the production of heat.
1. Electron Transport Chain: After glycolysis, the resulting molecules, NADH and FADH2, are used in the electron transport chain (ETC) located in the inner membrane of the mitochondria. NADH and FADH2 transfer high-energy electrons to the ETC, which then passes these electrons through a series of protein complexes. As the electrons move along the ETC, their energy is gradually released and used by the protein complexes to pump protons (H+) from the mitochondrial matrix into the intermembrane space. The proton gradient created by this process then allows ATP synthase to produce ATP through a process called oxidative phosphorylation.
2. Heat: During the conversion of glucose into ATP, some of the energy is lost as heat. This heat is produced through various processes in the cell, including the movement and transfer of molecules, the breaking and formation of chemical bonds, and the activities of enzymes. The release of heat is an unavoidable byproduct of cellular respiration.
Additionally, during cellular respiration, glucose is completely oxidized to carbon dioxide (CO2). This occurs in the mitochondria during the citric acid cycle (Krebs cycle) and is the final step in the breakdown of glucose. The carbon atoms in glucose are gradually released as carbon dioxide and are exhaled from the body as a waste product.