Effects of bridging activity in condensin knockout simulations. (A and B) Average mitotic chromosome width for control, condensin I, and condensin II knockout in simulations with and without bridging activity (A and B, respectively). In both scenarios (A and B), condensin I knockout was simulated with BBPs composed of longer chromatin loops, while condensin II knockout was simulated via shorter loops. The control and condensin I knockout cases do not seem very different between simulations with and without bridges. Instead, condensin II–depleted chromosomes do not change in width if condensin bridging activity is not included (see the “control” and “II K-O” bar in panel B), opposite to what is experimentally observed. For each of the six cases in panels A and B, the average and error bars are computed by employing 10 independent simulation runs.