Final answer:
RNA polymerases have been characterized from the three domains of life: Bacteria, Archaea, and Eukarya. Eukaryotes have three distinct RNA polymerases (I, II, III) that synthesize different types of RNAs. The complexity of eukaryotic transcription has been recognized with a Nobel Prize awarded to Roger Kornberg for his work in this area.
Step-by-step explanation:
RNA polymerases have been characterized from each of the three domains of life, which are Bacteria, Archaea, and Eukarya. In eukaryotes, there are three distinct RNA polymerases. RNA polymerase I synthesizes 18S, 5.8S, and 28S ribosomal RNAs (rRNAs), RNA polymerase II is responsible for synthesizing messenger RNAs (mRNAs), and RNA polymerase III transcribes transfer RNAs (tRNAs) as well as 5S rRNA and small nuclear RNAs (snRNAs). Each of these eukaryotic polymerases has a specific set of transcription factors necessary for the initiation of transcription. In contrast, prokaryotes use a single RNA polymerase to transcribe all their genes. This prokaryotic polymerase consists of multiple subunits, with the sigma (σ) factor playing a crucial role in transcription initiation. The Nobel Prize in Medicine in 2006 was awarded to Roger Kornberg for his discovery of the molecular basis of eukaryotic transcription.