Physics and Astronomy Colloquium

I will argue that the theory of stochastic processes provides a solid framework for describing biological systems. I will present two applications. The first concerns the development of algorithms capable of modeling large-scale multi-cellular systems, such as the early embryo. I will discuss the Subcellular Element Model (SEM), which is designed to simulate the interactions between thousands of three-dimensional, visco-elastic, deformable cells. The use of the SEM to understand one of the most fundamental embryonic processes - extension of the primitive streak - will be described. The second application is to cycling phenomena. I will discuss a new theoretical mechanism which predicts that intrinsic noise can induce oscillations in populations of small to intermediate size. I will illustrate this phenomena at two very different length scales, using the famous predator-prey system from ecology and non-linear feedback loops in genetic networks.