The main purpose of cellular respiration is to convert biochemical energy from nutrients into adenoside triphosphate, or ATP, a chemical energy needed by cells to perform certain functions. Muscle and brain nerve cells require energy that contains a high number of mitochondria to perform effectively.
Mitochondria burn sugar for fuel in cellular respiration and harvest energy from the sugar, thus changing sugar to ATP. The cell can then use this energy to perform other functions. Cells harvest energy from nutrients through fermentation and cellular respiration, also referred to as aerobic respiration. Both processes begin with the process of glycolysis, where glucose is broken down into ATP and pyruvic acid.