Glycolysis and gluconeogenesis are two metabolic pathways that occur in mammalian liver cells. Glycolysis is the process of breaking down glucose into pyruvate, while gluconeogenesis is the process of synthesizing glucose from non-carbohydrate precursors. Both pathways involve several enzymatic reactions, and the net ATP yield for the combined processes is zero because the ATP consumed in gluconeogenesis is equal to the ATP produced in glycolysis.Here are the reactions and enzymes involved in each step of glycolysis and gluconeogenesis:Glycolysis:1. Glucose + ATP Glucose-6-phosphate + ADP enzyme: hexokinase 2. Glucose-6-phosphate Fructose-6-phosphate enzyme: phosphoglucose isomerase 3. Fructose-6-phosphate + ATP Fructose-1,6-bisphosphate + ADP enzyme: phosphofructokinase 4. Fructose-1,6-bisphosphate Dihydroxyacetone phosphate + Glyceraldehyde-3-phosphate enzyme: aldolase 5. Dihydroxyacetone phosphate Glyceraldehyde-3-phosphate enzyme: triose phosphate isomerase 6. Glyceraldehyde-3-phosphate + NAD+ + Pi 1,3-bisphosphoglycerate + NADH + H+ enzyme: glyceraldehyde-3-phosphate dehydrogenase 7. 1,3-bisphosphoglycerate + ADP 3-phosphoglycerate + ATP enzyme: phosphoglycerate kinase 8. 3-phosphoglycerate 2-phosphoglycerate enzyme: phosphoglycerate mutase 9. 2-phosphoglycerate Phosphoenolpyruvate + H2O enzyme: enolase 10. Phosphoenolpyruvate + ADP Pyruvate + ATP enzyme: pyruvate kinase Gluconeogenesis:1. Pyruvate + ATP + HCO3- Oxaloacetate + ADP + Pi enzyme: pyruvate carboxylase 2. Oxaloacetate + GTP Phosphoenolpyruvate + GDP + CO2 enzyme: phosphoenolpyruvate carboxykinase 3. Phosphoenolpyruvate 2-phosphoglycerate reverse of glycolysis steps 9-3, using the same enzymes 4. Fructose-1,6-bisphosphate Fructose-6-phosphate + Pi enzyme: fructose-1,6-bisphosphatase 5. Fructose-6-phosphate Glucose-6-phosphate reverse of glycolysis step 2, using the same enzyme 6. Glucose-6-phosphate Glucose + Pi enzyme: glucose-6-phosphatase In glycolysis, there is a net production of 2 ATP molecules per glucose molecule. However, in gluconeogenesis, 6 ATP equivalents 4 ATP and 2 GTP are consumed per glucose molecule synthesized. Therefore, the net ATP yield for the combined processes of glycolysis and gluconeogenesis in a mammalian liver cell is zero.