Final answer:
The C-terminal domain of RNA polymerase II is crucial for mRNA synthesis regulation and undergoes phosphorylation. It also coordinates RNA processing steps such as splicing and polyadenylation. In prokaryotes, transcription termination mechanisms include rho-dependent and rho-independent pathways.
Step-by-step explanation:
The RNA polymerase II (RNA pol-II) enzyme in eukaryotic cells is responsible for transcribing most of the genes into messenger RNA (mRNA). Its C-terminal domain (CTD) must undergo specific modifications in order to regulate the transcription process. This includes phosphorylation events that allow the recruitment of various factors necessary for the initiation and regulation of mRNA synthesis.
Different processing steps are also essential for the newly transcribed RNA before it becomes a functional mRNA. This includes splicing of introns, capping at the 5' end, and polyadenylation at the 3' end. The CTD of RNA pol-II plays a critical role in coordinating these processing events.
In the context of termination of transcription, in prokaryotes, there are two forms: rho-dependent termination and rho-independent termination. Rho-dependent termination involves the rho protein, a helicase that disrupts the interaction between the nascent RNA and the DNA template. In contrast, rho-independent termination relies on the formation of a hairpin loop in the mRNA, leading to the stalling and release of the polymerase from the DNA template.