What characteristic describes the structure of the proteasome?

The structure of the proteasome is accurately described as a cylinder with caps and an active core. This cylindrical shape is essential for its function in protein degradation. The proteasome is composed of a core particle, which has a catalytic function, surrounded by regulatory particles or caps that control the entry of substrate proteins. These caps ensure that only appropriately tagged proteins, typically marked by ubiquitin, are directed into the core for degradation. The cylindrical structure allows for proteins to be unfolded and threaded into the core, where they are subsequently broken down into smaller peptides. This architecture is vital for maintaining cellular homeostasis by regulating protein levels and functions.