Final answer:
The single transcription regulator that can switch on all muscle-specific genes necessary for skeletal muscle cell specification is MyoD. This transcription factor is essential for the differentiation of precursor cells into skeletal muscle cells, by promoting the transcription of muscle-specific genes.
Step-by-step explanation:
Transcription factors are crucial for the process of cell differentiation and development. They bind to specific sequences of DNA and either promote or inhibit the transcription of genes, thus determining a cell's identity and function. In the context of skeletal muscle cells, a particular transcription factor known as MyoD plays a pivotal role. MyoD belongs to a family of muscle regulatory factors (MRFs) that are responsible for the regulation of muscle gene expression. These factors work in a highly coordinated fashion to ensure that muscle-specific genes are expressed at the right time and place during development.
In the absence of MyoD, precursor cells may not properly differentiate into skeletal muscle cells. However, when MyoD is present, it acts as a master regulator by binding to enhancer regions of muscle-specific genes, thereby activating their transcription. This action ultimately leads to the production of proteins that contribute to the structure and function of muscle fibers. The activity of MyoD and similar transcription factors showcases the intricate mechanisms of gene regulation that are fundamental to the differentiation and specialization of cells within a multicellular organism.