Figure 1.

Overview of carbohydrate metabolism. Simple sugars, such as glucose, fructose, or galactose, have different points of entry into glycolysis. A process referred to as gluconeogenesis can also generate glucose. Complex carbohydrates such as glycogen can also enter glycolysis. The hexosamine pathway generates glycoproteins and glycolipids, which are modified forms of glucose covalently attached to either proteins (glycoproteins) or lipids (glycolipids), that participate in important functions in signaling and as components of cell membranes.