After we consume food, many processes in our body break down the food to extract the needed carbohydrates and other molecules. These molecules then enter the blood stream and specific nutrients like glucose will diffuse out of the capillary and into a tissue cell. Cellular respiration will then oxidize the molecule causing the release of high energy molecules. The process is used to make ATP, which is the main energy storage source in cells. Cellular respiration is made up of 4 phases, with the first being glycolysis. Glycolysis breaks down the glucose molecule into 2 equal parts called pyruvate while also forming ATP and other energy sources. Pyruvate is then converted to Acetyl-CoA in the mitochondria. This stage produces carbon dioxide. The next stage is the Krebs cycle, where all of the material will be used to attain energy while forming carbon dioxide and water. The last step involves the electron transport chain, where energy storing molecules from the Krebs cycle are used to make ATP. Water is made in the process using oxygen that is brought into the blood stream from respiration.