The goal of this proposal is to understand the dynamical behavior of biological polyelectrolytes, especially DNA, in strongly interacting solutions. the interactions may be electrostatic, excluded volume, entanglement, or some combination. Such conditions are the norms inside cells. The work uses quasielastic light scattering (QLS), forced Rayleigh scattering (FRS), and small-angle x-ray scattering (SAXS) to shed light on how interactions influence the diffusional and binding behavior of biopolymers. Such influence can have major effects under physiologically relevant conditions.