From genotype to phenotype: computer-based modeling of gene expression with STELLA II.

STELLA II is a microcomputer program that is designed to simulate and animate the dynamics generated by biological systems in a quantitative fashion. The program employs the Macintosh user interface and includes a tool kit for assembling models, plus menus for setting parameters and selecting input or output. Quantitative relationships among components may be expressed with user-defined equations, graphical functions or data from spreadsheets. System dynamics are simulated by running the program after defining initial conditions, and results may be viewed immediately using windows for graphical or tabular plots. The present article describes how STELLA II may be used to simulate gene expression as an adjunct to experimentation or student-directed learning.