Glycolysis is a series of reactions that converts glucose into pyruvate and produce small amounts of ATP (adenosine triphosphate). The overall process of sugar breakdown to produce energy, however, is called respiration, and it takes several biochemical reactions, including glycolysis.
The process of glycolysis is very important in the human body. It is a part of the respiration process where energy is produced in our bodies. Glycolysis is the process whereby sugar is broken down to produce energy in the human body. This process is catalyzed by about ten enzymes which include, Kinases, Isomerases, and dehydrogenases, which are the key player enzymes in this process. In the process of glycolysis, sugar gets oxidized and released in the form of energy ATP energy. Glycolysis assists the body in the production of energy under low energy and inactive muscles. (Romano, 1996 pp. 234-289).
Energy containing sugars that are referred to as Hexoses which include galactose and fructose are funneled into glycolysis and produce energy in the human body. Human bodies have several metabolic processes to choose from, anabolic or catabolic, that are available from the sugars we consume. However, this depends on the energy that we require in our cells. When we are less active, the energy produced from the sugars will be stored as glycogen or fat for use when needed. When our bodies are active, the body cells often run out of adequate energy. The sugars are instantly broken down to produce energy, and the energy is released instantly into the cells. Energy from glucose is stored in various forms. The main form of storage is glycogen. The synthesis and the breakdown process of glycogen are controlled by a hormone called insulin. Long-term energy storage in cells is the conversion of energy, especially bulk energy, to fats that are stored in the body muscles. Glycolysis plays a very important role in the conversion process of energy to fats. Though it is a single part of the catabolic process, it is an ideal model of energy conversion. The bodies have a choice on what to do with the food we eat. (Robert, 2004 pp. 112- 201).
In yeast, the glycolysis process is a fermentation reaction, and it takes the following general equation;
glucose + 2ADP + 2P = 2CO2 + 2ATP. The difference between glucose, ethanol, and carbon dioxide, ADP, and ATP is that glucose, ethanol, and carbon dioxide are external substrates as well as products, and they are ingested and excreted, forming natural metabolic boundaries. The other two that is, ATP and ADP are which are the internal substrates and products, form artificial metabolic boundaries and connect with other cellular processes. The end products from these external substrates are from other cellular processes; for example, ATP is used in biosynthesis and growth while amino acids are for protein synthesis, and nucleotides synthesize nucleic acid. The process of glycolysis in yeast is basically anaerobic as I fermentation of yeast the process do not require oxygen or takes place in low oxygen concentration. In human beings, however, the process takes place only at a high concentration of oxygen as it involves the oxidation of sugars to release energy. Glycolysis in humans that is aerobic produces more energy from glucose than in anaerobic glycolysis in yeast which relies on the energy of glycolysis alone. The end product in glycolysis in yeast is lactate, while in humans, carbon dioxide and water are produced as by-products after energy is produced. In human cells, sometimes anaerobic glycolysis takes place in red blood cells and in some skeletal muscles where there is a shortage of oxygen. Higher demand of energy, for example, in the increase in cells, may cause the process of glycolysis to take place at low oxygen levels even in human beings.
References
Romano, H. (1996). Evolution of Carbohydrate Metabolic Pathways, New York: Prentice-Hall, pp. 211- 345.
Voet, D. and Voet, J. (2004). Biochemistry,3rdEdition, New York: John Wisley and Sons inc. pp. 112- 205.
Robert, A. (2004). Life on Earth, 4th Edition, New York: MacGraw Hill, pp. 112-213.