The structure of polymers with nonuniform curvature has been calculated for a semiflexible chain model, and a general expression for the persistence length and end-to-end distance is derived for a freely rotating chain. The statistical properties of molecules with one or more static bends or having a locally changed flexibility are analyzed in terms of the persistence length, but also the influence from heterogeneity of the molecular structure for an ensemble of chains is considered. Assuming the change in chain structure is caused, e.g., by the binding of ligand molecules, the effect of cooperativity on the molecular configuration is also treated.