Figure 5. Percolation transition in the mitochondrial network for c 1 = 0.1, L = 3·104.
(Upper part) Fractional size of the largest cluster in the system (blue stars) and the corresponding average number of segments per cluster in non-giant clusters (pink circles). The position of the critical point (arrow) corresponds to approximately 30% of largest cluster size fraction. For comparison, the experimentally determined largest cluster size fraction was 35±20% (dashed line). (Bottom part) Qualitative differences between subcritical, critical and supercritical regimes of the reticulum (c 2 = 1.7·10−6, 1.9·10−5 and 5.0·10−4 respectively, which corresponds to the ratios of end nodes (blue) to branching nodes (yellow) x 1/x 3≈31, 2.7 and 0.14 respectively): Although numbers of network edges (overall mitochondrial mass) are the same for the three configurations, the cell-wide connectivity is only possible above the critical value of tip-to-side fusion/fission ratio c 2≈2.0·10−5 (for clarity, bulk nodes are not shown and segments (green) are sketched of equal length).