Membranes are made of lipids and form when lipids are placed in an aqueous environment.  Lipids can come in different shapes and sizes and different lipids form different membrane phase domains such as gel-like or fluid-like domains.  The focus of this research is on membrane domains called “lipid rafts,” or membranes containing cholesterol.  In order to study lipid rafts, our laboratory at Colgate has developed a technique for determining the composition across phase domains of artificially formed lipid rafts.  Using a technique known as Fluorescence Resonance Energy Transfer (FRET), we can study the composition of these lipid rafts that spontaneously separate into distinct coexisting environments.  We     created 1294 samples of artificial membrane using varying amounts of cholesterol ranging from 0 to 26% of the membrane as well as ratios of lipids DLPC and DPPC.  We measured the membrane composition of these samples using FRET at temperatures of 10°, 20°, 30° and 42° Celsius.  Our results show that coexisting membrane domains form and behave in a consistent manner at these temperatures.  Our results also imply “tie line” trajectories within the regions of coexisting membrane domains.  While the membranes we studied form a relatively basic model, our results open the door for more biologically relevant studies in the immediate future.