Analysis of the contact probability in the absence of chromatin condensin loops. (A and B) Snapshots from simulations where chromatin loops have been removed and condensin bridges (green beads) can tightly bind chromatin on specific sites (red beads) and weakly bind any other sites (blue beads). Panel A shows the initial configuration where chromatin and bridges sterically interact. When attractive interactions between chromatin and bridges are switched on, the system reaches a new steady-state and condensin bridges form clusters around the specific chromatin sites (panel B; blue beads are here represented as transparent). (C) Contact probability versus genome distance for standard simulations (with loops) and for simulations represented in panels A and B (without loops). In the case without loops, it is not possible to observe the characteristic power law P(s) ∼ s−0.5 observed in mitotic chromosomes.