Cellular respiration is the process by which cells convert the energy stored in organic molecules, such as glucose, into a usable form called ATP. It occurs in multiple stages and involves a series of biochemical reactions.
In the first stage, glycolysis, glucose is broken down into two molecules of pyruvate, generating a small amount of ATP and NADH. Pyruvate then enters the mitochondria for further processing. In the second stage, the Krebs cycle, the pyruvate molecules are completely oxidized, releasing more ATP, NADH, and FADH2, as well as carbon dioxide as a waste product.
The final stage, oxidative phosphorylation, takes place in the inner mitochondrial membrane. Here, the high-energy electrons carried by NADH and FADH2 are passed along the electron transport chain, creating a proton gradient. This gradient drives the synthesis of ATP through a process called chemiosmosis.
Overall, cellular respiration is a vital process for all living organisms as it provides the necessary energy for cellular activities and is essential for sustaining life.