Glucose can be synthesized from non-carbohydrate precursors, such as pyruvate and lactic acid. Although glycolysis and gluconeogenesis have some of the same enzymes in common, the two pathways are not simply the reverse of each other.
Synthesis of glucose from non-carbohydrate sources.
Major precursors are lactate and alanine
lactate – is from active skeletal muscles
glycerol – is from lipid catabolism
amino acids - diet and protein catabolism
Used to maintain blood glucose levels when glycogen supplies are low or depleted.
Major site of occurrence is the liver, but also occurs in kidney.
Designed to make sure blood glucose levels are high enough to meet the demands of brain and muscle (cannot do gluconeogenesis).