Final answer:
True, a single transcription regulator can trigger the formation of a specialized cell type or an entire organ.
Step-by-step explanation:
The question asks whether a single transcription regulator, when expressed in the appropriate precursor cell, can trigger the formation of a specialized cell type or an entire organ. The statement is True. Transcription factors are crucial in the differentiation and specialization of cells. For example, the Hox genes, through their transcription factors, regulate the formation of specialized cells and tissues, illustrating shared ancestry in this conserved strategy for communication between cells. Similarly, the sex determination process in Drosophila is regulated by the gene slx, whose product influences other genes like tra, dsx, and fru to generate specific sexual characteristics. This exemplifies the broader role of transcription factors in regulating gene expression and the subsequent impact on cell differentiation and specialization.