Glycolysis is a metabolic process by which a single molecule of glucose is broken down into two pyruvate compounds. Each glucose molecule releases two NADH and ATP molecules during the reaction. Glycolysis is carried out by all living organisms as a mechanism for gaining the necessary energy to sustain life.
There are 10 steps in the glycolysis reaction. These steps must take place in order to break a six-carbon glucose molecule down into two separate three-carbon pyruvate molecules. For this reaction to occur, two ATP molecules and several enzymes must be present.
Glycolysis is carried out in the cytoplasm of cells and is a prerequisite for other biological processes. Depending on the environment around the cell, pyruvate molecules can be utilized in two different methods following the completion of glycolysis: oxidized and fermented.
The Krebs Cycle is initiated in the cell if oxygen is present, and results in oxidized pyruvate molecules. The Krebs Cycle facilitates the generation of six NADH, two ATP and two FADH molecules, all of which can be used by the body for a variety of reactions necessary for life. In an environment lacking oxygen, the two pyruvate molecules generated by glycolysis are converted into lactic acid through a fermentation process.