Answer:
The process you are referring to is cellular respiration. Cellular respiration is the process by which cells extract energy from glucose and other nutrients to produce ATP, the energy currency of the cell. The process occurs in three main stages: glycolysis, the citric acid cycle (also known as the Krebs cycle), and the electron transport chain.
During glycolysis, glucose is broken down into two molecules of pyruvate in the cytoplasm of the cell. In the process, some ATP is produced, and high-energy electrons are released and carried by the molecule NADH.
The pyruvate molecules then enter the mitochondria, where they are further broken down in the citric acid cycle, releasing more high-energy electrons, which are also carried by NADH and another molecule called FADH2.
The high-energy electrons carried by NADH and FADH2 are then passed through a series of protein complexes in the electron transport chain, located in the inner membrane of the mitochondria. As the electrons are passed along, they release energy that is used to pump protons (H+) across the membrane, creating a gradient of H+ ions. The flow of H+ ions back across the membrane through ATP synthase drives the production of ATP.
In summary, the high-energy electrons released during the breakdown of glucose are carried by NADH and FADH2, and are used to generate a proton gradient in the electron transport chain, which drives the production of ATP. The high-energy electrons still contain most of the chemical energy of the original glucose molecule, and this energy is gradually released and harnessed to produce ATP through the process of cellular respiration.