What Happens During Cellular Respiration?

During cellular respiration, glucose breaks down into carbon dioxide and water. This process releases a store of energy, or ATP, that cells can use for their needs.

Cellular respiration is a process by which glucose, or sugar, oxidizes intocarbon dioxide and water, releasing energy in the form of adenosine triphosphate (ATP). The process occurs partially in the cytoplasm, which is the material within the living cell, and partially in the mitochondria, an organelle found in most cells.

Cellular respiration starts in the cytoplasm with one glucose molecule splitting into two molecules of pyruvic acid, which is an organic acid that occurs during many metabolic processes. The pyruvic acid shuttles into the mitochondria where it is converted into acetyl coenzyme A (acetyl CoA), an important biochemical molecule that can be broken down further.

During the Citric Acid Cycle, the presence of oxygen strips the hydrogen molecules off the acetyl CoA two at a time until there are none left. All that remains of the glucose is carbon dioxide, which is a waste product, and water. The Citric Acid Cycle produces a lot of nicotinamide adenine dinucleotide (NADH), which carries electrons from the hydrogen molecules down an electron transport chain, resulting in the production of ATP.