Final answer:
During transcription initiation, RNA polymerase II is recruited to the DNA promoter region and its activity is catalyzed by transcription factors. This process leads to the synthesis of pre-mRNA, which ultimately undergoes processing to become mature mRNA for protein production.
Step-by-step explanation:
Transcription Initiation of RNA Polymerase II
During transcription initiation, RNA polymerase II is recruited and catalyzed by transcription factors. The process begins with the recognition of promoter sequences by these factors. The most typical eukaryotic promoter contains a TATA box to which the TATA-binding protein (TBP) component of TFIID binds. Then, other transcription factors and RNA polymerase II assemble to form the preinitiation complex. Once this complex is formed, RNA polymerase II is released from the transcription factors to proceed with elongation, synthesizing pre-mRNA in the 5' to 3' direction.
The role of RNA polymerase II in the cell is significant, as it is responsible for transcribing the majority of eukaryotic genes into mRNA. These mRNAs are critical as they contain the information required for synthesizing proteins within the cell. The synthesized pre-mRNAs undergo further processing to become mature mRNAs, ready to be translated into proteins. Therefore, the correct fill-in-the-blank statement would be: During transcription initiation, RNA polymerase II is recruited and catalyzed by transcription factors.