Glycolysis is the metabolic process by which glucose is converted to pyruvate. The process of glycolysis is important in producing energy for the cell, particularly in anaerobic conditions. The word glycolysis literally means "sugar splitting" or "sugar breaking"; this accurately describes the process of glycolysis, in which a 6-carbon sugar molecule is broken into two 3-carbon molecules. Glycolysis consists of ten separate reactions, each catalysed by a different enzyme. Glycolysis is regulated by three different control enzymes. The first of these enzymes is hexokinase which phosphorylates glucose, turning it into glucose-6-phosphate. Therefore making it less permeable trapping it inside the cell and also making it more reactive. The second is phosphofructokinase. This enzyme allows the production fructose-1,6-bisphosphate and is the rate-limiting step. The final control enzyme is pyruvate kinase which controls the rate of production of pyruvate, which is the final product of glycolysis. For each molecule of glucose that goes through the process of glycolysis, there is a net gain of 2 ATP molecules, 2 NADH molecules and 2 water molecules.