Carbohydrates are part of the four main classes of biomolecules and are made up of hydrogen, oxygen, and carbon atoms. The three simplest forms of carbohydrates are sugar, starch, and fiber. Pictured above is pasta which is full of starch. Starch is made of many glucose molecules bonded together, making it a polysaccharide. With the help of enzymes starches are broken down into glucose molecules and provide energy for the brain and muscle function.