Glycogen is a polysaccharide. Polysaccharides are carbohydrates made up from a large number of monosaccharides joined together by glycosidic bonds formed in condensation reactions. Glycogen, sometimes referred to as “animal starch” is made up from many glucose molecules, joined together by 1,4 and 1,6 glycosidic bonds. It has a branched structure that is directly linked with its ability to release a big amount of energy in very little time as it is required in animal tissues such as muscles or liver tissues. In order to release energy, the bonds break with a process called hydrolysis and energy is released thus making it a very appropriate storage molecule as its numerous branches allow for it to be broken down rapidly and release the energy needed for various cellular functions such as cellular respiration. It is found in animal tissues as they require a lot more energy due to the higher level of activity in comparison to plant tissues where starch is enough to cover the energy needs.