Glucose has a chemical formula of: C6 H12 O6 That means glucose is made of 6 carbon atoms, 12 hydrogen atoms and 6 oxygen atoms.
A starch, is a long string of glucose(polysaccharides) and/or other simple sugar molecules(monosaccharides) chemically bonded together. A carbohydrate is an organic compound and is found in many of our foods. Potatoes, rice, pasta, corn and breads contain large amounts of starch. Our bodies cannot absorb these large compounds so our digestive system breaks them up into smaller molecules called simple sugars(monosaccharides).
The breakdown of starches begins with the saliva in the mouth. Our saliva contains an enzyme called amylase that begins to break the chemical bonds holding the large carbohydrate molecules(starches) together. The amylase works somewhat like a pair of scissors breaking the bonds between each simple sugar.
Once starch digestion is complete, single molecules of glucose(monosaccharides) are left. Glucose is a small enough molecule to be absorbed by the small intestine. Once it is absorbed, insulin from the pancreas picks it up and carries it to all of the cells in your body.
The mitochondria in each cell break the glucose apart to release energy. The process in which glucose is broken down is called cellular respiration. Both autotrophs and heterotrophs perform respiration. When glucose is broken down, chemical and thermal energy is produced.