Macromolecule chitin is a complex polysaccharide containing amino sugars and chemically modified sugars (e.g., glucosamine, $\mathrm{N}$-acetyl galactosamine, etc). Polysaccharides are long carbohydrate molecules of monosaccharide units joined together by glycosidic bonds. They have a general formula $\mathrm{C}_x\left(\mathrm{H}_2 \mathrm{O}\right)_y$.