Among the main events of transcription initiation of TATA-containing genes in eukayotes are the recognition and binding of the TATA-box by the TATA-binding protein (TBP) to start the preinitiation complex formation on the nucleosomal DNA. Using the equilibrium equation for step-by-step TBP/TATA-binding, we have analyzed 69 experimental datasets on the characteristics of biologicacally important features altered by TATA-box mutations. Among these features, the TBP/TATA-complex parameters, the transcription level, the activity of gene products, yeast colony growth at a dose of growth inhibitor (phenotype), and the heterogenity of the response of a population to unspecific environmental stress have been described. Significant correlations were found between in silico prediction for TBP/TATA affinity and experimental data for in vivo and in vitro test-systems based on 15 cell types of 19 species, RNA polymerases II and III, and natural, recombinant or mutant TBP. Such an invariant impact of the step-by-step TBP/TATA-binding on the biological activity of complex systems, from a molecule to a population, might be due to the fact that TBP/TATA-complex formation precedes specific steps of transcription machinery assembly, which provide the multivariant jigsaw puzzle according to the expression pattern of each eukaryotic gene.