Glycogen like starch is a condensation polymer of α - D glucose. Just as glucose is stored in plants in the form of starch it is stored in the form glycogen in human beings. It is present in liver, muscles and brain. When body needs glucose, enzymes breakdown glycogen to provide glucose. It is also present in yeast and fungi.
The main difference between glycogen and starch is that starch is made up of amylose and amylopectin where as glycogen consists of a structure almost same as amylopectin with large number of branching, (amylose has a linear structure and amylopectin has a branched structure with branching after every 25-30 molecules). Glycogen has branching after every 10-15 molecules.
