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Simulating Lipid Membranes: Self-Assembly, Self-Repair, and Self-Reproduction
Tim Hutton
University College London


Cell membranes in nature have some very interesting properties. They are made of simple fat molecules (lipids) that self-assemble when immersed in water into bilayer sheets and spheres (vesicles). The self-assembly happens simply as an energy minimisation - the surrounding water repels them and pushes them together into certain shapes. These membranes will reconfigure to repair any damage, and can have different proteins embedded in them that can change their flexibility and perform more sophisticated functions such as gate-keeping and communication. Harnessing these useful properties in a computer simulation is a difficult problem - the cost of a full molecular dynamics (MD) simulation is prohibitive due to the large number of atoms that are interacting. In this talk I will present some work from the field of artificial chemistry, where membranes have been implemented in many different ways, ranging from accurate to abstract. One of the most interesting systems was presented in Naoaki Ono's PhD thesis in 2001, and represents lipids molecules as line segments, moving in two dimensions. With the right forces between the particles all the properties mentioned above emerge naturally. I will present this model in detail and discuss extensions to it, including the modelling of protocells that grow and divide.