Physics of active matter in living cells

Living matter is highly dynamic and organizes in complex patterns and spatial structures. A fundamental problem in biology is to understand how the interaction of many different molecules and genes gives rise to a fascinating diversity of patterns and morphologies. Many dynamic processes in cells are generated with the help of active processes such as those mediated by motor molecules. Molecular motors are driven by the chemical energy of a fuel and generate movements and forces on molecular scales. Such active processes give rise to unconventional mechanical behaviors and spontaneous movements of gel-like materials in the cell. Such active gels play a key role in many dynamic processes such as cell division and cell locomotion. Spatial structures in cells can also be organized with the help of phase separation of different components. Co-existing liquid phases can provide distinct environments with different chemistry. Spatial patterns of molecular organization can be formed by the interplay of phase separation and chemical reactions. I will discuss examples of cellular systems which make use of such physical principles to generate spatial structures and dynamic behaviors that play an important role for cellular function.