This simulation shows a dynamic molecular model of the bacterial cytoplasm, giving us a spectacular glimpse of the crowded conditions of the interior of a cell over a brief 15-microsecond time span. The model includes 50 of the most abundant types of macromolecules reported in Escherichia coli, for a total concentration of 275g/L. This "steric energy" simulation shows a model of macromolecular diffusion based on Brownian dynamics and steric interactions between the molecules. This can be compared the the "full energy" model that also includes electrostatic and hydrophobic interactions.