| Glycogen | |
| Glycogen is the form in which animals store carbohydrates. Glycogen is a heavily branched polymer of alpha-glucose molecules, pictured on the right, covalently linked at carbon 1 of one molecule to carbon 6 or 4 of the next molecule. The arrows indicate the sites at which the molecule can link to other glucose molecules. |  | 
| The heavy branching of glycogen is shown on the right. Heavy branching allows for quick breakdown of the molecule by enzymes to release glucose. |  |