Over the last twenty years the dramatic growth of fluorescence mycroscopy techniques and advances in microscopic manipulation of single molecules as DNA has been accompanied by the migration of a huge number of scientists, coming from the most different disciplines, toward the new "Eldorado" of the modern biological research. The work presented in this book reflects these recent developments in applying typical physics tools to the study of the bacterium Escherichia coli. This amazing 2.5 micrometer cell is for biological physicists equivalent to the hydrogen atom for atomic physicists. The Min-proteins play a decisive role in the correct selection of the division site through pole-to-pole oscillations. A quantitative study of such a phenomenon is presented in this book. Important physical quantities characterizing the system, such as the in-vivo Min-protein mobility are measured, then deterministic and probabilistic mathematical models are proposed and discussed. Being limited on a very specific subject and based on a PhD thesis, this monograph is mainly, but not exclusively, aimed to researchers and PhD students working in the field.