Glycolysis

Glycolysis is a cytoplasmic pathway which breaks down glucose into two three-carbon compounds and generates energy. The process produces two molecules of pyruvate, two molecules of ATP, two molecules of NADH, and two molecules of water.

The most common pathway of glycolysis was described by Gustav Embden, Otto Meyerhof, and Jakub Karol Parnas. Glycolysis is therefore known as the Embden–Meyerhof–Parnas (EMP) pathway.

Glycolysis takes place in the cytoplasm of a cell and does not require oxygen. Glycolysis is controlled by the properties of three regulatory enzymes: hexokinase, phosphofructokinase 1 and pyruvate kinase.

Glycolysis is followed by the Krebs cycle during aerobic respiration. Under aerobic conditions, pyruvate can diffuse into mitochondria, where it enters the citric acid cycle and generates reducing equivalents in the form of NADH and FADH2.

In the absence of oxygen, the cells make small amounts of ATP as glycolysis is followed by fermentation. Glycolysis produces 2 ATP per glucose molecule, and thus provides a direct means of producing energy in the absence of oxygen.
Glycolysis