Fig. 2

Overview of the GAL network and the simulation process. a. The GAL network in S. cerevisiae with its activity reported by a P _GAL1 -YFP reporter. Transcription of GAL1, GAL3, GAL80, and the reporter are controlled by the transcription factor Gal4p. Gal80p represses Gal4p and is in turn repressed by the inducer Gal3p and Gal1p in the presence of galactose. b. As a cell grows, both the volume and the number of gene and network copies will change. c. The simulation and sampling process for the 22-h simulation. Each cell in the figure represents 1000 cells; the initial population is simulated for 11 h, resulting in a population of ~42,000 cells; from this population 2000 cells are sampled and simulated for an additional 11 h to produce the final population of cells