Chemically, guar gum is an exo-polysaccharide composed of the sugars galactose and mannose. Lactose is a disaccharide of galactose plus glucose. This endosperm consists of a large polysaccharide of galactose and mannose. The common dietary monosaccharides galactose, glucose and fructose are all reducing sugars. Lactose is a disaccharide composite of two simple sugars, glucose and galactose. Milk contains several different carbohydrate including lactose, glucose, galactose, and other oligosaccharides. Monosaccharides include glucose, fructose and galactose. Common sugars added include galactose, "N"-acetylglucosamine, fucose and sialic acid. It can also hydrolyze lactose into galactose and glucose which will proceed into glycolysis. Arabinogalactan is a biopolymer consisting of arabinose and galactose monosaccharides. Raffinose is a trisaccharide composed of galactose, glucose, and fructose. Addition of galactose and sialic acid occurs in the "trans" cisternae. Uridine plays a role in the glycolysis pathway of galactose. Galectins essentially bind to glycans featuring galactose and its derivatives. Thus, Oxidation to galactonate serves as an alternate pathway for metabolizing galactose.