Every cell in your body must generate a usable form of energy called adenosine triphosphate (ATP), which is necessary for most cellular functions, including muscle contraction, respiration and cardiovascular activity. All cells in the body have the ability to utilize glucose as a fuel for ATP production through a process known as glucose oxidation.
Glucose
According to "Advanced Nutrition and Human Metabolism," glucose is classified as a monosaccharide. Glucose can be obtained in the diet through consumption of starchy foods such as bread and pasta. Foods with simple sugars, such as fruits and sweets, are also sources of glucose. Endogenous glucose production also occurs in the liver and kidneys.
Oxidation
Molecules such as glucose can undergo a chemical process known as oxidation. The oxidation of a molecule slightly changes its chemical properties. According to “Biochemistry Primer for Exercise Science,” oxidation can occur through the addition of oxygen or the loss of electrons from an atom or molecule. These processes are usually catalyzed by enzymes such as oxidases and dehydrogenases.
Glycolysis
Glycolysis is a biochemical pathway that initiates the oxidation of glucose. According to "Advanced Nutrition and Human Metabolism,” glycolysis occurs in the cytoplasm of every cell in the body. The goal of glycolysis is to split the six-carbon glucose molecule into two three-carbon molecules of pyruvate. This is accomplished through a series of chemical reactions. A small amount of ATP is produced in the process of pyruvate formation from glucose.
Citric Acid Cycle
Under aerobic conditions, the oxidation of glucose continues in the mitochondria of the cell. Here the pyruvate formed in glycolysis enters another biochemical pathway called the citric acid cycle. According to “Advanced Nutrition and Human Metabolism,” the goal of the citric acid cycle is further oxidation through the removal of electrons from pyruvate and other intermediates. This is accomplished by several dehydrogenase enzymes.
Electron Transport Chain
According to “Advanced Nutrition and Human Metabolism,” the oxidation of glucose concludes as the electrons gathered in the citric acid cycle are carried through another series of enzymes called the electron transport chain, also located in the mitochondria of the cell. The movement of electrons through the electron transport chain generates the energy needed to produce ATP. In addition to ATP, the complete oxidation of glucose also yields carbon dioxide and water.
References
- “Advanced Nutrition and Human Metabolism (fifth edition)”; Gropper, Smith, Groff, Wadsworth; 2009
- “Biochemistry Primer for Exercise Science (third edition)”; Houston; 2006
