The sugar used by cellular respiration is broken down into adenosine triphosphate (ATP), which is the usable form of energy for cells.
During the process of cellular respiration, glucose, a simple sugar, undergoes a series of chemical reactions. Initially, glucose is converted into pyruvate through a process called glycolysis, which occurs in the cytoplasm of the cell. This process yields a small amount of ATP directly.
Then, in the presence of oxygen, the pyruvate is transported into the mitochondria, where it enters the citric acid cycle (also known as the Krebs cycle). Here, it is further broken down, and additional ATP is produced along with electron carriers like NADH and FADH2.
Finally, those electron carriers enter the electron transport chain, where the bulk of ATP is generated through oxidative phosphorylation using oxygen. In essence, the breakdown of glucose ultimately leads to the production of ATP, which is essential for various cellular processes, serving as the primary energy currency in all living cells.