  We investigate an analytically tractable toy model for thermally induced
polymorphic dynamics of cooperatively rearranging biofilaments - like
microtubules. The proposed 4 -block model, which can be seen as a
coarse-grained approximation of the full polymorphic tube model, permits a
complete analytical treatment of all thermodynamic properties including
correlation functions and angular fourier mode distributions. Due to its
mathematical tractability the model straightforwardly leads to some physical
insights in recently discussed phenomena like the "length dependent persistence
length". We show that a polymorphic filament can disguise itself as a classical
worm like chain on small and on large scales and yet display distinct anomalous
tell-tale features indicating an inner switching dynamics on intermediate
length scales.
