What is the primary role of RNA polymerase II in eukaryotic transcription?

The primary role of RNA polymerase II in eukaryotic transcription is to transcribe protein-coding genes into RNA. This process involves the synthesis of messenger RNA (mRNA) from a DNA template, which is a critical step in gene expression. RNA polymerase II binds to promoter regions of genes and initiates transcription by unwinding the DNA and synthesizing a complementary RNA strand using ribonucleotide triphosphates.

This action specifically facilitates the production of mRNA, which will then undergo several processing steps before being translated into proteins by ribosomes. The ability of RNA polymerase II to accurately transcribe the coding sequences for proteins is fundamental for cellular function and regulation. Other roles mentioned in the options, such as DNA repair, ribosome binding, and mRNA processing, are performed by different cellular mechanisms or enzymes, highlighting the specific and essential function of RNA polymerase II in the transcription process.