We seek to construct physical and mathematical models of life. Such models allow us to test our understanding of how living systems function and how they respond to human imposed stimuli. One system is a genomically and chemically complete model of a minimal cell. This cell is a hypothetical bacterium with the fewest number of genes possible. Such a minimal cell provides a platform to ask about the essential features of a living cell and forms a platform to investigate "synthetic biology." A second system is "Body-on-a-Chip" (or microphysiological system) which is a microfabricated, microfluidic system with cells or tissue constructs representing various organs in the body. That physical model is based on a physiologically based pharmacokinetic-pharmacodynamics (PBPK-PD) model. The ratio of organ sizes and the flow to each component is physiological. It can be constructed from human or animal cells and used in drug discovery development, or to predict response to exposure to environmental chemicals. Both the computer and the physical models provide insight into the underlying biology and provide new tools to make use of the understanding to provide benefits to society.