The evolution and structure of the active region NOAA 0139 on the basis of radio observations obtained at RATAN-600, SSRT, and RT-22 are investigated. By means of a wavelet analysis as well as images obtained at the space orbital stations SOHO and TRACE, it is shown that observed dynamics of the S-component of microwave emission may be caused by the change of number and power of elementary flare events. The strong depression of emission revealed at short wavelengths in the course of evolution of active region is explained by the decrease of fluxes of accelerated electrons, which are responsible for the high temperature of the transition region and upper chromosphere of the Sun. The results obtained show evidence for an essential contribution of elementary flare events to the heating of the coronal plasma.