Computational Model of Artificial Life




This research project involves studies of computational models for aspects of early life forms. We have investigated self-replication, an important feature shared by many early life and pre-life forms, using cellular automata models. Using this model, a family of non-trivial self-replicating structures have been created which are substantially smaller and simpler than those created by previous methods, starting with Von Neumann's conjecture 40 uears ago. An implication of this work is that self-replication ability does not have to be associated with life forms in a more advanced stage. The current focus of this project is on the development of computational models for the formation of membranes and other forms of biological compartment structures known as lipsomes from lipid-like polar molecules (amphiphiles). Lipsomes such as single layer micelles and reverse micelles and bilayer membranes have been conjectured to be crucial for the evolution of early life. It is not difficult to reproduce some of these structures in chemical experiments. However, without computational models, it is difficult to investigate at the molecular level the behavior of these structures and the mechanism leading to their formation. Recently, we have developed one such model based on modeling inter-molecular forces stemmed from the basic physical and chemical properties of amphiphiles (e.g., hydrophobicity, electro-statics, and gravity). The computer simulations of this model demonstrated that simple structures such as micelles can be formed from a pool of randomly distributed polar particles. Two possibilities will be further explored toward the formation of bilayer membranes. One is the formation of membranes from monolayers caused by external perturbation or internal surface tension; and another from collision of several micelles. The resulting model will then be used to investigate important properties of membranes, include the effects of environmental factors (e.g., temperature, pH-value of the solvent, and the concentration of lipids) on the formation of different types of lipsomes; asymmetric permeation of chemicals through the walls of membranes; fission of large membranes to form smaller ones, etc.



Contact Yun Peng, .