A simple collective model for description of the effect of the alpha-cluster degree of freedom in the structure of heavy and superheavy nuclei is suggested. The alpha-chains of nuclei based on some of the Pb isotopes are considered. It is shown based on the experimental data on nuclear binding energies that the effect of the strong coupling of the alpha-mode and the octupole correlations in Rn, Ra, Th and U isotopes is manifested. The excited states associated with the alpha-cluster degree of freedom are considered and their excitation energies are estimated as being larger than 1.7[Formula: see text]MeV. This corresponds to [Formula: see text]-decay probability from the ground state to these states 4–7 orders of magnitude less than [Formula: see text]-decay between the ground states. Although, their structure is determined by the same dynamical variable as the structure of the ground states.