Glycolysis is the metabolic pathway that converts glucose into pyruvate, generating ATP and NADH in the process. In glycolysis, the net ATP yield per molecule of glucose is 2 ATP. The key enzymes involved in glycolysis are:1. Hexokinase2. Phosphofructokinase-1 PFK-1 3. Pyruvate kinaseGluconeogenesis is the metabolic pathway that generates glucose from non-carbohydrate precursors, such as lactate, glycerol, and certain amino acids. Since gluconeogenesis is essentially the reverse of glycolysis, it consumes ATP rather than producing it. The net ATP consumption in gluconeogenesis per molecule of glucose is 6 ATP 4 ATP and 2 GTP .The key enzymes involved in gluconeogenesis are:1. Pyruvate carboxylase2. Phosphoenolpyruvate carboxykinase PEPCK 3. Fructose-1,6-bisphosphatase4. Glucose-6-phosphataseRegulation of glycolysis and gluconeogenesis differs mainly at the level of these key enzymes. In glycolysis, the main regulatory enzyme is phosphofructokinase-1 PFK-1 , which is allosterically activated by AMP and fructose-2,6-bisphosphate F2,6BP and inhibited by ATP and citrate. This ensures that glycolysis is active when energy levels are low and inactive when energy levels are high.In gluconeogenesis, the main regulatory enzyme is fructose-1,6-bisphosphatase, which is allosterically inhibited by AMP and activated by citrate. This ensures that gluconeogenesis is active when energy levels are high and inactive when energy levels are low. Additionally, fructose-2,6-bisphosphate F2,6BP inhibits fructose-1,6-bisphosphatase and activates PFK-1, thus coordinating the regulation of glycolysis and gluconeogenesis.Another level of regulation occurs through hormonal control. Insulin, which is released in response to high blood glucose levels, promotes glycolysis and inhibits gluconeogenesis. In contrast, glucagon, which is released in response to low blood glucose levels, inhibits glycolysis and promotes gluconeogenesis.In summary, glycolysis has a net ATP yield of 2 ATP per molecule of glucose, while gluconeogenesis consumes 6 ATP per molecule of glucose. The key enzymes involved in each pathway are regulated differently to ensure that glycolysis and gluconeogenesis are active under appropriate conditions, maintaining glucose homeostasis in the body.