Final answer:
The σ subunit of the RNA polymerase is involved in the initiation phase of bacterial transcription, where it helps the polymerase to locate and bind to the promoter region.
Step-by-step explanation:
The phase or step involved in the comprehensive single-cycle problem of Algorithm Lo 7-1, 7-5, 7-6 is related to the process of bacterial transcription. Specifically, the question is asking about the role of the sigma (σ) subunit of the RNA polymerase. The sigma subunit is primarily involved in the initiation phase of bacterial transcription. During initiation, the RNA polymerase binds to the promoter region of the DNA, begins to unwind the DNA strands, and starts the synthesis of the RNA transcript. The sigma subunit helps the RNA polymerase to identify the promoter regions ensuring that transcription is initiated at the correct location on the DNA.