Final answer:
RNA polymerase II is essential for the transcription of eukaryotic genes into pre-mRNA, which is then processed into mature mRNA. This enzyme operates in the nucleus and is responsible for creating the RNA templates that are necessary for protein production.
Step-by-step explanation:
RNA polymerase II (RNA Pol II) is a critical enzyme in the process of transcription, where it synthesizes pre-messenger RNA (pre-mRNA) from a DNA template in the nucleus of eukaryotic cells. Transcription by RNA Pol II involves creating a complementary RNA copy of the gene's DNA sequence. This precursor RNA molecule, referred to as pre-mRNA, undergoes several processing steps to become mature mRNA, ready for translation into proteins.
RNA Pol II is responsible for the transcription of the vast majority of eukaryotic genes, especially those that encode for proteins. After transcription, pre-mRNAs need to be spliced where introns are removed and exons are joined together, capped at the 5' end, and polyadenylated at the 3' end, resulting in mature mRNAs that are then transported out of the nucleus to the ribosomes for protein synthesis.
In contrast, other polymerases, such as RNA polymerase I and RNA polymerase III, transcribe non-protein coding RNA like ribosomal RNA (rRNA) and transfer RNA (tRNA), which are involved in the protein synthesis machinery and other cellular functions.