Most analyses of interactions between biological macromolecules are performed in dilute aqueous solutions, conditions far removed from those found inside a living cell (one need only think of the difference between water and the solution found inside a fresh egg to appreciate this enormous difference). The cell interior contains enormous numbers of macromolecules which crowd each other. This crowding, involving classical physical chemical principles, dramatically affects interactions between macromolecules and causes DNA to "condense" to a compact structure. Intracellular macromolecular crowding and DNA condensation can be copied in vitro. We propose to apply techniques such as fluorescence spectroscopy, fluorescence polarisation, dynamic light scattering and the imaging of single DNA molecules using time-resolved fluorescence microscopy and atomic force microscopy to complexes of proteins and DNA prepared in novel solution environments designed to mimic intracellular conditions. Theoretical methods, based upon polymer and soft condensed matter physics play an important role in interpreting results. These results can then be tested in vivo using advanced live cell imaging and intracellular spectroscopy.