How does a cell know how big it is?

Reaction–diffusion theory explains how molecular diffusion and reaction rates can set the scale of biological patterns. Yet structures such as the nucleus and mitotic spindle scale with the cell containing them, suggesting a mechanism that measures cell size. Jané Kondev presents mathematical models of chemical networks capable of this measurement and compares their predictions with quantitative experiments. The talk uses cell-size sensing to show how physical reasoning, explicit mathematical models, and measurement can resolve questions in cell biology.