ABSTRACT
The biological cell is a main building block of all living systems. If we could take a look inside the cell (see Fig. 1.1), we would find a very complex dynamic system filled with a solution (called cytosol) of various chemical species (proteins, nucleic acids, lipids, ions, small organic molecules, etc.) and cross-linked by polymeric filamentous structures (called cytoskeleton). It would also show multiple separate compartments, a large number of spatially and temporally varying chemical reactions, significant fluxes of molecules and other particles (vesicles and organelles) between different regions of the cell, and dynamically changing cytoskeleton and cellular boundaries (Lodish et al. 2007, Alberts et al. 2007, Bray 2001)[95, 4, 23]. If we wait longer, we would witness the amazing process of cell division when a new cell, identical to the original one, is created. These complex dynamic phenomena bring to mind a suggestion (although still not quite perfect) that the biological cell is very similar in many aspects to a large city with its highly energetic life (see Fig. 1.2). As in a large city, the biological cell has different districts (compartments), cellular materials are moved in different directions mostly along specific routes, cytoskeleton filaments (roads and streets) constantly grow and shrink, and the position of cell borders is varying.
