Balanced biosynthesis and trigger threshold resulting in a double adder mechanism of cell size control

Leilei Li

Figure 3. The stochastic trajectories and the scale-free property of cell size. (a) The stochastic trajectories of chemical populations, P, T, R, Q, I, D and volume V versus time t. Parameters of the dynamics systems are k = 3000 h−1, Σ = 3 ∗ 10−5 μm3 h−1, KD = 4 ∗ 10−12 h−1, KI = 6 ∗ 10−12 h−1, dR = dQ = dT = 0.1 h−1, Dc = 200, Ic = 200, Dr = 0, Ir = 0, and the other parameters of the model are shown in the table 1. The population values in figure 3(a) have been adjusted to make all of populations shown on the same figure by some multiplier factors. (b) The frequency distribution of cell division size, birth size, added size, and inter-division time in the steady state. The average division cell size ⟨Vd⟩ is 3.279 μm3, average birth cell size ⟨Vb⟩ = 1.642 μm3, average added cell size ⟨Δ⟩ = 1.637 μm3, average division time ⟨τ⟩ = 0.723 h. (c) The frequency distribution of cellular variables is re-scaled by their respective means. The curves denoted by cell division size, cell birth size, added size and doubling time stand for Vd/⟨Vd⟩, Vb/⟨Vb⟩, Δ/⟨Δ⟩ and τ/⟨τ⟩. The coefficient of variation of those cellular variables are 0.071, 0.093, 0.113, 0.094.