Beyond Simplifications: Overlooked Physics of Macromolecular Behaviors in Living Cells

Simplifications are key to understanding the complex physical behaviors of biomacromolecules within living cells. However, in cell-sized spaces─micrometer-scale compartments enclosed by lipid membranes─the molecular organization, phase behavior, and reaction dynamics are influenced by confinement, high molecular concentrations, and membrane interfacial effects. Studies have shown that these factors, which are often overlooked or ignored during simplification, are critical for deducing the physics of intracellular processes. This perspective highlights the recent findings on the molecular behaviors of cell-sized spaces and emphasizes the need to consider cell-sized space effects, molecular diversity, and nonequilibrium dynamics to elucidate the physics of living cells. A deeper understanding of these fundamental principles bridges the gap between molecular biology and physics. In addition, it will refine our understanding of cellular organization, inspire developments in biomaterials, and contribute to polymer science.