RNA polymerase II

Definition

RNA polymerase II is a crucial enzyme in eukaryotic cells responsible for synthesizing messenger RNA (mRNA) from DNA during the transcription process. It plays a key role in gene expression by converting genetic information encoded in DNA into RNA, which can then be translated into proteins. This enzyme also facilitates the processing of pre-mRNA, including capping and polyadenylation, which are vital for mRNA stability and translation efficiency.

5 Must Know Facts For Your Next Test

1. RNA polymerase II transcribes protein-coding genes as well as some non-coding RNAs, playing a central role in gene regulation.
2. It requires several general transcription factors to initiate transcription, forming a complex that binds to the promoter region of genes.
3. The enzyme moves along the DNA template strand, unwinding the DNA helix and synthesizing RNA in the 5' to 3' direction.
4. After RNA synthesis, RNA polymerase II is involved in capping the 5' end of the mRNA molecule with a modified guanine nucleotide, which protects the RNA from degradation.
5. The enzyme also has a carboxy-terminal domain (CTD) that undergoes phosphorylation, which is critical for recruiting processing factors necessary for mRNA maturation.

Review Questions

• How does RNA polymerase II interact with transcription factors during the process of gene transcription?
  • RNA polymerase II interacts with transcription factors by forming a transcription initiation complex at the promoter region of a gene. These transcription factors help recruit RNA polymerase II to the appropriate site on the DNA and assist in unwinding the double helix. This collaboration ensures that RNA polymerase II can efficiently start transcribing the gene into mRNA.
• Discuss the significance of pre-mRNA processing in relation to RNA polymerase II's function and gene expression.
  • Pre-mRNA processing is crucial because it transforms newly synthesized RNA into a mature mRNA molecule capable of being translated into protein. RNA polymerase II plays a key role in this process by facilitating capping at the 5' end and adding a poly-A tail at the 3' end. Additionally, splicing occurs where introns are removed and exons are joined together, ensuring that only coding sequences are included in the final mRNA. This processing enhances mRNA stability and translation efficiency.
• Evaluate how mutations affecting RNA polymerase II could impact cellular function and organismal development.
  • Mutations affecting RNA polymerase II could severely disrupt gene expression patterns essential for cellular function and organismal development. If RNA polymerase II is unable to effectively transcribe genes due to structural or functional alterations, it could lead to insufficient production of critical proteins necessary for cell growth, division, and differentiation. This could result in developmental disorders or diseases such as cancer, where improper regulation of gene expression is often observed. Understanding these mutations helps elucidate their roles in various biological processes and disease states.

Related terms

Transcription Factors: Proteins that bind to specific DNA sequences to regulate the transcription of genes, often working alongside RNA polymerase II to initiate transcription.

Eukaryotic Transcription: The process by which genetic information from DNA is transcribed into RNA in eukaryotic cells, involving multiple steps and regulatory mechanisms.

Pre-mRNA Processing: The modifications that pre-mRNA undergoes after transcription and before it becomes mature mRNA, including capping, splicing, and polyadenylation.