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Solving problems in cell biology with simple molecular-mechanical models


Speaker: Sam Walcott, John Hopkins University
Location: 1147 MSB
Start time: Mon, Jan 31 2011, 1:10PM

Cells are complex mechanochemical systems. In the cell interior, proteins undergo chemical reactions in the presence of mechanical forces. For many cellular processes, the identity of these proteins and many of their chemical interactions are known. How mechanical forces influence these processes is much less clear. I study how mechanics influences chemical reaction rate, and how, in turn, mechanics influences cellular processes. To demonstrate my approach, I consider the problem of cell mechanosensation -- how a cell senses and adapts to mechanical properties, particularly the stiffness, of its environment. I use an extremely simple mechanical model, a point mass on a spring in the vicinity of an attractive potential, to predict (and then validate) how properties of chemical reactions change under load. With some clever mathematical tricks originally applied to muscle mechanics, I assemble ensembles of these molecular systems into a model for biological friction. I then use this friction model to explain the behavior of cells placed on surfaces of different stiffness, thereby suggesting that cell mechanosensation can be explained, at least qualitatively, through molecular mechanics. This work emphasizes the importance of molecular mechanics in cell biology.