Depletion of cohesin or condensin alters the elastic response of pericentric chromatin in cells deleted of KIP1. (A) A Hookean spring has a linear force versus the extension curve in which the force applied is proportional to length (F = −k(x−x₀), where F = force, k = spring constant, x₀ = rest length, and x = extended length). The circles to the left of the force extension curve denote the structure of the spring at different values of force. A WLC has an exponential force versus extension curve of F = (k_BT/P) [1/4(1 − x/L)⁻² − 1/4 + x/L], where F = force, k_B = Boltzmann constant, T = temperature, P = persistence length, L = contour length, and x = extended length. Gray lines to the right of the force extension curve denote the structure of the WLC at low force (random coil) and an extended chain (wavy line) at higher force. Large rectangles denote linear force versus extension, whereas the slim rectangle denotes nonlinear portions. (B) Metaphase spindle length was measured between the spindle pole bodies (Spc29-RFP) in Gal-H3, mcm21Δ, brn1-9, and mcd1-1 single mutants with KIP1 and double mutants with kip1Δ. The error bars represent SD. Statistically different (P < 0.05) KIP1 versus kip1Δ spindle lengths are marked by an asterisk. (C) Spindle length variation was measured by tracking the spindle pole bodies every 35 s for 11.7 min in Gal-H3, mcm21Δ, brn1-9, and mcd1-1 single mutants with KIP1 and double mutants with kip1Δ. The error bars represent 95% confidence. Spindle length variation that is statistically different (P < 0.05) from that of WT is marked with an asterisk. Mutants with the same number of asterisks are statistically similar (P > 0.05), whereas those with a different number of asterisks are statistically different (P < 0.05).