This textbook is for all students of the natural sciences interested in the physical concepts describing fundamental cellular processes. For example, the phenomena of diffusion and the mechanics of macromolecules and the cell membrane are treated and illustrated with many examples. Furthermore, the formation of the fibrous proteins of the cytoskeleton as well as enzyme kinetics and the functioning of molecular motors are discussed. This compact book builds on a two-semester lecture entitled Biophysics in the Cell, given at the Technical University of Munich. To emphasize different approaches and thus make them more comprehensible, important formulas are often derived in different ways. "By the way" sections, highlighting historical or current backgrounds and the scientific zeitgeist of the respective research, enrich the material in an entertaining way. Attractive, clear and modern illustrations give the book a special charm in addition to the technically up-to-date andcomprehensibly presented content.  From the contents: - Origin and structure of cells, basic concepts of biophysics and important basics of thermodynamics and statistical mechanics - Passive motion by diffusion: physical description of diffusion, lattice models, diffusion in a potential, biochemical reactions - Mechanics of beams, polymers and membranes: elastic properties of biological components, forces, bending, stretching, stretching and rupture of the cell membrane and cytoskeleton. - Active movement and enzyme kinetics: functioning of enzymes, molecular motors and the dynamics of fibre proteins in the cytoskeleton