Stochastic GTP-cap model of microtubule growth and collapse
Microtubules switch stochastically between growing (polymerization) and shrinking (depolymerization) phases — "dynamic instability". A GTP-tubulin cap at the tip stabilizes growth; catastrophe (collapse) occurs when hydrolysis consumes the cap. The transition rates fcat (catastrophe) and fres (rescue) set the average dynamic parameters. This drives chromosome capture during mitosis.