What Is Aerobic Respiration? What Is the Role of Glucose in Aerobic Respiration? What Is Aerobic Respiration? Respiration is a metabolic process by which an organism obtains energy. Aerobic respiration is a specific type of respiration in which oxygen reacts with glucose to provide water, carbon dioxide and energy in the form of adenosine triphosphate (ATP). Aerobic respiration is performed by all animal cells. Simplified Reaction The following equation shows the simplified overall reaction that releases energy from glucose and oxygen: C6H12O6 + 6 O2 ' 6 CO2 + 6 H2O + energy. A molecule of glucose (C6H12O6) reacts with six molecules of oxygen (O2) to produce six molecules of carbon dioxide, six molecules of water and energy. This energy is stored in the form of ATP. ATP ATP is a chemical that's used to store energy in living cells during aerobic respiration. It contains three atoms of phosphorus, which are bound to the adenosine part of the molecule in a chain. The last phosphorus atom may be split from the rest of the molecule in the presence of water to produce adenosine diphosphiate (ADP), which releases energy. The following equation shows this reaction: ATP + H2O ' ADP + P + energy. The reverse reaction is used to store energy in the form of ATP: ADP + P + energy ' ATP + H2O. Glycolysis Glycolysis is one of the intermediate stages in aerobic respiration. This process converts glucose into two molecules of pyruvate (CH3COCOO), a molecule of hydrogen and two molecules of ATP. The following simplified equation shows this reaction: C6H12O6 + 2 ADP + 2 P ' 2 CH3COCOO + H2 + 2 ATP. Krebs Cycle The pyruvate molecules produced in glycolysis go through a subsequent series of reactions known as the Krebs cycle. Each molecule of pyruvate produces an enzyme called acetyl-CoA, which is used to produce an additional molecule of ATP as well as waste products of water and carbon dioxide. Each molecule of glucose therefore produces two molecules of ATP through the Krebs cycle, since glycolysis produces two molecules of pyruvate from one molecule of glucose. Electron Transport Aerobic respiration also produces energy through electron transport. This process uses the hydrogen released in glycolysis to create a difference in the concentration of hydrogen ions (H+) across a cellular membrane. This electrochemical difference is known as a chemiosmotic potential and is a type of potential energy that can be used to produce ATP from ADP. The net yield of energy from the electron transport phase of aerobic respiration is 29 to 30 molecules of ATP for each molecule of glucose. Read more: http://www.livestrong.com/article/75703-aerobic-respiration/#ixzz1zKmEUt4x What Is the Role of Glucose in Aerobic Respiration? During aerobic respiration, cells obtain energy in the presence of oxygen through a series of reactions known as the citric acid cycle. Glucose is a molecule that provides a key reaction intermediate necessary for these reactions to occur. Glucose is a six-carbon sugar molecule that gets broken down into two, three-carbon pyruvate molecules. These pyruvate molecules, in the presence of oxygen, can enter the citric acid cycle, producing a significant amount of energy for the cell. Glycolysis Glucose can be obtained directly from the diet, or by the breaking down of glycogen, a polymer of glucose molecules. During glycolysis, glucose is metabolized by the cell to produce energy. Glycolysis is not very efficient in terms of energy production, but the process itself generates a series of intermediates that can be used for other processes. One such intermediate is pyruvate. In the absence of oxygen, pyruvate can be converted to lactic acid or alcohol through a process known as fermentation. However, in the presence of oxygen, during aerobic respiration, pyruvate can enter the citric acid cycle. The Citric Acid Cycle The citric acid cycle is a series of reactions that ultimately produce a significant amount of energy for the cell. This cycle can only occur under aerobic conditions, that is, conditions in which sufficient oxygen is present. In the presence of oxygen, the pyruvate molecules formed at the end of glycolysis can enter the citric acid cycle by reacting with a compound called Acetyl-CoA. During this reaction, carbon dioxide is released. In fact, carbon dioxide is released in a number of steps during the citric acid cycle. This is, in part, an explanation of why aerobic respiration involves breathing in oxygen and breathing out carbon dioxide. Electron Transport Chain By definition, aerobic respiration requires oxygen. Oxygen is required because it is needed in the electron transport chain. The electron transport chain of a cell is a series of reactions that pair chemical reactions between electron donors and electron acceptors to the transfer of protons across a cellular membrane. In aerobic respiration, oxygen is the ultimate electron acceptor. The transfer of electrons creates a proton gradient. When the protons travel back across the membrane, flowing down the gradient, energy in the form of molecules called ATP, or adenosine tri-phosphate, is created. If there is no oxygen present, the gradient cannot be set up, and these reactions cannot occur. Glucose While glucose can provide energy to the cell through glycolysis, this process is not very efficient. An input of two ATP energy molecules gets the reaction started, but in the end, only four ATP energy molecules are created. Glucose provides a greater role for more efficient energy production by providing the pyruvate molecules for entrance into the citric acid cycle. At the end of the citric acid cycle, 36 ATP energy molecules are created for every 1 glucose molecule completely metabolized. Sources of Glucose Glucose can be obtained directly from the diet. Glucose is a six-carbon monosaccharide sugar molecule, also known as dextrose, or simple table sugar. It is also part of a long chain of energy storage molecules called glycogen. When cells need more glucose to produce more energy, glycogen can be broken down to release individual glucose monomers, which can then enter the glycolysis pathway. Eventually the resulting pyruvate molecules can enter the citric acid cycle, provided oxygen is present. Read more: http://www.livestrong.com/article/137517-what-is-role-glucose-aerobic-respiration/#ixzz1zKl2GpXc