Final answer:
Rho-independent transcription termination occurs when the RNA polymerase encounters a region rich in C-G nucleotides and forms a stable hairpin structure. This hairpin causes the polymerase to stall when it begins to transcribe a region rich in A-T nucleotides, leading to the release of the mRNA transcript.
Step-by-step explanation:
Rho-independent transcription termination is regulated by specific sequences in the DNA template strand. As the RNA polymerase nears the end of the gene being transcribed, it encounters a region rich in C-G nucleotides. The mRNA then folds back on itself, and the complementary C-G nucleotides bind together, forming a stable hairpin structure. This causes the polymerase to stall when it begins to transcribe a region rich in A-T nucleotides. The weak interaction between the complementary U-A region of the mRNA and the template DNA, combined with the stalled polymerase, leads to enough instability for the core enzyme to break away and release the new mRNA transcript.