Caspase Cascade & the Apoptotic Point of No Return

This simulator models the core biochemical logic of programmed cell death: initiator caspase-9 cleaves procaspase-3 into active executioner caspase-3, which loops back to activate more caspase-9 — a positive-feedback amplifier — while the inhibitor XIAP tries to sequester every active caspase-3 molecule it meets. Two hundred and forty molecules, rendered as an instanced particle cloud drifting inside the cytoplasm, switch between inactive zymogen, active enzyme and inhibitor-bound states as a live set of mass-action rate equations integrates each frame. Drive the cascade with an apoptosome trigger pulse, dial up or down XIAP's defensive capacity, release SMAC/DIABLO to blunt that defense, and watch the system tip past a bistable commitment threshold — the molecular point of no return that separates a cell that survives a stress signal from one that dismantles itself.