Amylopectin. Computer-generated molecular model of amylopectin. Amylopectin is composed of carbon (green), hydrogen (grey/white) and oxygen (red). Amylopectin is a polysaccharide that is a component of starch. It makes up 70-80% of the carbohydrate. Saccharides consist of rings of four or five carbon atoms and one oxygen atom. Attached around the ring are hydroxyl (OH) groups. Polysaccharides comprise hundreds of monosaccharide units joined in chains. Amylopectin is formed from units of the monosaccharide glucose. The chains branch, forming the basis of the structure of starch granules.