Definition for Glycolysis
From Biology Forums Dictionary
1) A metabolic pathway that breaks down glucose to pyruvate.
2) Glycolysis is the breakdown of glucose to pyruvic acid in the cytoplasm of a cell. It is called an anaerobic process, because it does not require oxygen. Glycolysis provides a net gain of 2 ATP and generates 2 pyruvic acid molecules from each glucose molecule. The ATP produced by glycolysis is thus only a small fraction of that produced by aerobic metabolism, in which the breakdown of the 2 pyruvic acid molecules in mitochondria would generate 34 ATP. Yet, because it can proceed in the absence of oxygen, glycolysis can be important when the availability of oxygen limits the rate of mitochondrial ATP production.
In most skeletal muscles, glycolysis is the primary source of ATP during peak periods of activity. The glucose broken down under these conditions is obtained primarily from the reserves of glycogen in the sarcoplasm. Glycogen is a polysaccharide chain of glucose molecules. Typical skeletal muscle fibers contain large glycogen reserves, which may account for 1.5 percent of the total muscle weight. When the muscle fiber begins to run short of ATP and creatine phosphate, enzymes split the glycogen molecules apart, releasing glucose, which can be used to generate more ATP. As the level of muscular activity increases and these reserves are mobilized, the pattern of energy production and use changes.