What is the difference between cellulose and glycogen?

Cellulose and glycogen are both carbohydrates, but cellulose is a structural polysaccharide found in plants, while glycogen is an energy storage polysaccharide in animals.

Cellulose and glycogen are two types of carbohydrates that play different roles in organisms. Cellulose is a complex carbohydrate, or polysaccharide, that is used by plants as a structural component. It is found in the cell walls of green plants, giving them rigidity and strength. The structure of cellulose is linear, consisting of glucose monomers linked by β-1,4-glycosidic bonds. This unique bond makes cellulose indigestible to most animals, except those like cows and termites that have symbiotic bacteria in their digestive system capable of breaking down these bonds.

On the other hand, glycogen is the main form of carbohydrate storage in animals and fungi. It is stored primarily in the liver and muscles and is quickly mobilised to meet the energy needs of the body. Glycogen has a branched structure, with glucose units linked by α-1,4-glycosidic bonds and branching points created by α-1,6-glycosidic bonds. This structure allows for the rapid release of glucose when energy is needed.

In terms of their chemical structure, both cellulose and glycogen are polymers of glucose, but the type of linkage between the glucose units differs. In cellulose, the glucose units are flipped relative to each other, creating a straight, rigid structure. In glycogen, all the glucose units are oriented in the same direction, resulting in a more flexible, branched structure.

IB Biology Tutor Summary: Cellulose and glycogen are both glucose-based polymers, but differ in structure and function. Cellulose, found in plant cell walls, is linear and tough, providing structural support. Glycogen, found in animals and fungi, is branched and serves as a quick energy source. The key difference lies in their glucose linkages, affecting their digestibility and physical properties.