Final answer:
RNA polymerases in Prokaryotes and Eukaryotes exhibit high structural similarity, despite differences in the complexity of the polymerase structure and the transcription initiation process.
Step-by-step explanation:
RNA polymerases in Prokaryotes and Eukaryotes have a high structural similarity. Although eukaryotes use three different RNA polymerases (I, II, and III), and prokaryotes use a single type, their fundamental process of transcription is similar.
In prokaryotes like E. coli, the RNA polymerase is composed of five subunits that form the polymerase core enzyme. The eukaryotic RNA polymerases are each made up of 10 or more subunits and are structurally distinct from the bacterial polymerase, but archaeal RNA polymerases are more closely related to eukaryotic polymerases. This also reflects how transcription initiation is more similar between archaea and eukaryotes, with archaeal mRNA transcription resembling that of eukaryotes but with fewer initiation factors. Unlike prokaryotic polymerases, eukaryotic RNA Polymerase II does not possess helicase activity, which is facilitated by the TFIIH protein in eukaryotes.
The architectures of the promoters also show similarities; both prokaryotes and eukaryotes have a sequence similar to the -10 sequence in prokaryotes, with eukaryotes having a TATA box.