Cell dynamics aims to understand biological complexity in the context of the modular organization of the cell. The three-dimensional structure of the cell gives biological systems the ability to sequester, tightly regulate, and increase the efficiency of many cellular systems. However, this structure is not static. The organelles, specialized domains, and macromolecular machines inside the cell are extremely dynamic, responding both to the internal state of the cell and to external stimuli. Systems biology with cell biology combine to help study the origins and dynamics of organelles to understand the networks that underlie cellular function and dysfunction.