Diffusion in living cells: simple or anomalous?

Diffusion in living cells: simple or anomalous?

Cecile Fradin, McMaster University

The live cell is by definition a dynamic environment, with different types of motions happening at each length scale. At the molecular level, macromolecules such as proteins or nucleic acids need to be able to move around the cell rapidly, but also in a somewhat organized manner. The contribution of diffusion to those molecular transport processes is still an object of controversy. In the case of simple diffusion, the diffusing particles have a mean square displacement proportional to time, <r2>~t, but often subdiffusive behaviors are observed for macromolecules in cells, where this relationship is no longer true. Here, I will discuss experiments we have done to test the hypothesis that the crowded conditions encountered in the cellular environment leads to anomalous diffusion, with <r2>~tα. And I will illustrate the importance of diffusion in cellular processes, whether simple or anomalous, by considering the example of the establishment of morphogenetic gradients during development.