ABSTRACT
Chromatin has become an enormous field of research, with scientists from a wide variety of experimental and computational backgrounds, that at present no entirely coherent picture of the field exists. In order to "understand chromatin" one needs to properly understand the physical determinants of the polymer-protein complex, and this across multiple spatial and temporal scales and to understand the role of non-equilibrium, irreversible, ATP-consuming processes, which are key to many specific regulatory functions. The chapter describes a two-fluid model for the viscoelastic hydrodynamics of chromatin including solvent and polymer, and distinguishes between equilibrium and non-equilibrium "events", termed "scalar" and "vector". It will be very interesting to link the behaviors to precise biological processes, but nevertheless these results show the relevance of ATP-dependent processes for chromatin as a whole. The ATP-dependent events are essential as processes that increase specificity of the interactions, alongside the equilibrium processes involving cooperative interactions between molecules.
