Acetyl Co-A is common to respiration mediated breakdown of fats, carbohydrates and proteins. Glucose and fructose are phosphorylated to give rise to glucose 6-phosphate by the activity of the enzyme hexokinase. Glucose-6-phosphate then converts into fructose 6 phosphate and further to fructose 1-6-bisphosphate. Pyruvic acid is the end product of glycolysis.