Biochemistry

gluconeogenesis turns into glucose, which again enters the muscles with blood and is included in metabolic processes. The biological significance of the glycolysis process is primarily in the formation of energy-rich phosphorus compounds. In the first stages of glycolysis, two ATP molecules are consumed (hexose and phosphoffuctokinase reactions). At subsequent stages, four ATP molecules are formed (phosphoglyceratekinasc and pyruvatekinase reactions). In addition, two NADH 2 molecules are formed, each of which, during biological oxidation on mitochondria, releases three ATP molecules. Consequently, as a result of glycolysis, eight ATP molecules form from a single glucose molecule. From an energetic point of view, glycolysis is inefficient, since a large amount of carbohydrates is used for energy production. However, the physiological significance of this process is extremely high, since it allows the body to perform its functions in conditions of insufficient oxygen supply, and the final products of glycolysis (pyruvate and lactate) are substrates of aerobic oxidation. The value of glycolysis is also determined by the facts that during the corresponding reactions substances are formed that are necessary for the biosynthesis of certain vital compounds. For example, phosphodioxyacetone is used for the biosynthesis of simple and complex lipids. Thus, it is glycolysis that prepares “ processed foods ” , which are subsequently oxidized to CO 2 and H 2 O under aerobic conditions. Louis Pasteur, studying the relationship between anaerobic and aerobic oxidation, drew attention to the inhibition of glycolysis during respiration. This phenomenon is called the "Pasteur effect". Inhibition occurs at the stage of conversion of fructose-6-phosphate to fructose-l,6-diphosphate. The significance of the Pasteur effect, i.e., the transition of oxygen from anaerobic glycolysis to respiration, consists in switching the cell to a more economical way of obtaining energy. One of the reasons for the suppression of glycolysis by respiration is the competition for inorganic phosphate and ADP. In some cells, such as cancer cells, glycolysis proceeds more intensively. With the growth of malignant tumors, the reverse Crabtree effect occurs to the Pasteur effect - inhibition of respiration by glycolysis. Aerobic carbohydrate oxidation Cells that are not sufficiently supplied with oxygen can partially or fully exist at the expense of the energy of glycolysis. 226