A Stochastic Model of the Yeast Cell Cycle Reveals Roles for Feedback Regulation in Limiting Cellular Variability
Fig 2
Deterministic and stochastic simulations of the model.
A (top panels). Deterministic simulation of the changing concentrations of a representative sample of the proteins in the model (left) and the changing numbers of mRNA molecules for some of the genes (right). Cell volume, V(t) (in fL, black line), increases exponentially during each cycle and drops by a factor of 2 at cell division (indicated by arrowheads in each panel). The cell-cycle regulated genes show oscillatory dynamics of mRNAs, whereas for unregulated genes (e.g. CLN3, CDH1, CDC14) the mRNA level stays constant throughout the cell cycle. B (bottom panels). Stochastic simulations, in the same format as the top panels. The numbers of protein molecules N in a cell of volume V (in fL) has been converted into concentration C (in nM) by the equation C = 1.67 N/V. Hence, a concentration of 100 nM in a cell of volume 50 fL corresponds to ~3000 molecules.