Living organisms need energy to carry out vital functions. To obtain this energy all cells must carry out a process called respiration. In almost all living things on Earth, energy comes from glucose metabolism. Essentially all living things require basic sugars to perform respiration. Cellular respiration is a process in which cells produce the energy they need to survive. It is a series of reactions and metabolic processes that occur in the cells of organisms and are essential for all living cells. In this process biochemical energy is converted from nutrients into adenosine triphosphate (ATP). ATP produced during cellular respiration is the universal energy for all living organisms. The chemical energy of food molecules is released and partially captured in the form of ATP in the process of cellular respiration. Glucose is most commonly used as an example to examine the reaction of cellular respiration, but other fuels that can be used are fats, proteins, and carbohydrates. The formula for cellular respiration is glucose + oxygen --> carbon dioxide + water + energy and the chemical equation is C6H12O6 + 6O2 --> 6CO2 + 6H2O + ATP. Cellular respiration can be divided into three metabolic processes: glycolysis, Krebs cycle, and oxidative phosphorylation. Each of these occurs in a specific region of the cell. The first phase of cellular respiration is glycolysis, which occurs in the cytosol. Glycolysis literally means the breakdown of glucose. The process of glycolysis is both anaerobic without oxygen and aerobic with oxygen. Aerobic is when the cytosol converts 1 molecule of glucose into 2 molecules of pyruvate. Glucose cannot be converted to pyruvate without the help of 2 NAD+ and 2 ATP. Once glycolysis is c...... at the center of the paper molecule ......sugar) and breaks it down. Fermentation is the second phase of anaerobic respiration. It starts with pyruvate, the end product of glycolysis. Depending on the organism, ethanol (a fancy name for alcohol) or lactate (lactic acid) can be produced by fermenting pyruvate. CO2 released during fermentation, all ATP is produced during glycolysis. Since 2 ATPs are produced in glycolysis, 2 ATPs are formed from each glucose molecule during anaerobic respiration. In summary, cellular respiration can be anaerobic or aerobic. All this depending on whether there is oxygen or not. Aerobic respiration can produce up to 38 ATP with a single glucose molecule, while anaerobic respiration produces 2 ATP in total. Aerobic respiration is more efficient than anaerobic respiration because it can produce significantly more ATP than anaerobic respiration..