Figure 4.

Langevin simulations for stochastic cell size dynamics in fast and slow growth conditions. For (A)–(D), blue trajectories correspond to a relatively fast-growing condition with $⟨k⟩=0.06{\min }^{-1}$ and red to a relatively slow-growing condition with $⟨k⟩=0.03{\min }^{-1}$. (A) Length versus normalized time $t/\tau$ for a single generation, where τ is cell-cycle duration. The dashed black curve is a fit of deterministic super-exponential growth Eq. 3. The transparent bands surrounding each deterministic curve represent the standard deviation in length fluctuations (${\sigma }_{\delta L}=0.066\mu \mathrm{m}$). (B) Length versus absolute time for several generations. (C) Width versus $t/\tau$ for a single generation in normalized time. The solid black shows individual cell mean width. The transparent band around each cell mean width line represents the standard deviation in width fluctuations (${\sigma }_{\delta w}=0.017\mu \mathrm{m}$). (D) Width versus absolute time for several generations. Cell mean width is represented with solid black lines, while population mean width is represented by dashed black. The transparent band around each population mean width line represents the standard deviation in intergenerational fluctuations (${\sigma }_{w_0}=\left(0.02\mu m\right)\exp \left(\left(16.19\min \right)⟨k⟩\right)$). To see this figure in color, go online.