Extended Data Fig. 5: The cell-mass model parameters used to define the biosynthetic rates are structurally identifiable according to profile likelihood analysis.

We considered 9 parameters defining the rates of protein, lipid, polysaccharide, RNA and DNA biosynthesis in the model of cell-mass dynamics during the cell cycle (details in Supplementary Methods). For each fixed parameter value (x-values of empty circular markers), we optimized the model over the rest of parameters and reported the objective function value (y-values of empty circular markers). The red diamond marker shows the result of the free optimization in which the parameters of interest were not fixed. The yellow internal plot zooms in on the proximity of the red marker. For each of the 9 parameters, the objective function in the optimization where the parameter is free proves to be the smallest compared to the optimizations where the parameter is fixed to a value different from the optimal one, which demonstrates that the 9 parameters of interest are structurally (globally) identifiable according to profile likelihood approach [main-text ref. ⁴³]. The optimal value of \(f_{lipids}^{\,err}\) is at the lower boundary of feasibility; this parameter cannot be smaller, otherwise the rate of lipid biosynthesis becomes negative at some cell-cycle phases. The optimal value of \(f_{polysaccharides}^{\,err}\) is at the upper boundary of feasibility defined by the variability of the measurement of the polysaccharide biosynthesis activity. The profile likelihood analysis was performed using the input data set where the replicate measurements of each biosynthetic activity were averaged (the respective simulation results are showed via the solid line in Fig. 3b–d).