The role of RNA polymerase II is to:
a. Transcribe proteins
b. Transcribe mRNA
c. Translate proteins
d. Translate mRNA
The correct answer and explanation is:
The correct answer is: b. Transcribe mRNA
RNA polymerase II is a key enzyme in the process of transcription, specifically responsible for synthesizing messenger RNA (mRNA) in eukaryotic cells. Transcription is the first step in the expression of genes, where the information encoded in the DNA is copied into RNA. RNA polymerase II binds to a gene’s promoter region, which is a specific sequence of DNA that signals the start of the gene. It then unwinds the DNA and reads the template strand to create a complementary RNA strand.
RNA polymerase II does not transcribe proteins directly. Instead, it creates an mRNA molecule that serves as a template for protein synthesis during translation, which occurs in the ribosome. The mRNA carries the genetic information from the DNA in the nucleus to the ribosome in the cytoplasm, where proteins are synthesized.
The transcription process by RNA polymerase II involves several stages: initiation, elongation, and termination. During initiation, RNA polymerase II binds to the promoter and starts RNA synthesis. In elongation, it moves along the DNA, adding RNA nucleotides that are complementary to the DNA template strand. Finally, in termination, the polymerase reaches a signal sequence that signals the end of transcription, releasing the newly synthesized mRNA.
RNA polymerase II is specific to protein-coding genes, making it distinct from other RNA polymerases like RNA polymerase I, which transcribes rRNA genes, and RNA polymerase III, which transcribes tRNA and other small RNA genes.