Polysaccharides are natural, amorphous carbohydrates with the general formula C₆H₁₀O₅ₙ. Starch, the most abundant plant carbohydrate, is made of α-D-glucose units and consists of two parts: amylose, a water-soluble linear polymer with glycosidic bonds, and amylopectin, a water-insoluble branched polymer with 2 linkages. Amylose makes up about 20% of starch, while amylopectin comprises 80%. Cellulose, found in cell walls and cotton, is a linear polymer of β-D-glucose units linked via glycosidic bonds. Unlike starch, cellulose has high tensile strength due to hydrogen bonding and is not digestible by humans. Cellulose is also the precursor to many industrial derivatives.