Describe the structure of glycogen and explain why it is a suitable molecule to store energy.

Glycogen is a branched polymer of glucose that is stored in the liver and muscles of animals. Its structure is similar to that of starch, which is a polymer of glucose found in plants, but it is more highly branched. The branching occurs through alpha-1,6-glycosidic bonds, which link together linear chains of glucose molecules that are themselves linked through alpha-1,4-glycosidic bonds.

The highly branched structure of glycogen makes it a suitable molecule to store energy because it allows for rapid and efficient access to glucose when energy is needed. The linear chains of glucose can be rapidly broken down by the enzyme glycogen phosphorylase, which cleaves off glucose molecules from the ends of the chains. The branching of the glycogen molecule means that there are many ends to the chains, allowing for many glucose molecules to be released at once. This is important for providing a rapid source of energy during times of high demand, such as during exercise.

Additionally, the compact structure of glycogen means that it can be stored in large amounts within the liver and muscles without taking up too much space. This allows animals to store a significant amount of energy in a small space, which is important for survival during times when food may be scarce. Overall, the highly branched and compact structure of glycogen makes it an efficient and effective molecule for storing and rapidly accessing energy when needed.