Explain why glycogen is well suited to its role as a storage carbohydrate in animal muscle cells.

Glycogen is a polymer of many glucose monomers linked by α‑1,4‑glycosidic bonds, with α‑1,6‑branches every 8–12 units. Because it is insoluble in cell fluid, it does not alter the cell’s water potential or osmotic balance. The highly branched structure gives many non‑reducing ends, so glucose can be released rapidly by phosphorylase when energy is required. Finally, the compact, branched arrangement allows large amounts of glucose to be stored in a small volume, keeping the cell’s size and shape unchanged.