The iBioSim tool is being developed to facilitate the construction and simulation of synthetic genetic circuits. In this project, we have created a user interface that is similar to those used to construct schematic diagrams which are familiar to electrical engineers. Promoters, chemical species, and biological relationships can be placed visually on a schematic diagram. Another enhancement was the creation of a new simulation visualization tool which allows the user to associate chemical species with color schemes, opacity, and cell size. This tool allows the user to see the cells behavior as if through a microscope.