Gene Regulation in Eukaryotic Cells

Overview

• Eukaryotic gene regulation is more complex than prokaryotic due to the complexity of eukaryotic cells.
• Gene regulation occurs at different levels, primarily focusing on transcription.

Components of a Eukaryotic Gene

1. Exons
   • Segments of DNA that code for polypeptides.
2. Introns
   • Non-coding segments of DNA removed during RNA splicing.
3. Transcription Start Site
   • The location where transcription begins.
   • RNA Polymerase II binds here to initiate transcription.
4. Promoters
   • Complex structures compared to prokaryotic cells.
   • Core Promoter: Includes the TATA box, found upstream of the start site.
   • Upstream Promoters: Vary between genes and bind regulatory proteins.
5. Enhancers
   • DNA segments located far from the gene, either upstream, downstream, or within the gene itself.
   • Bind transcription factors and enhance transcription rate.

Detailed Explanation

Transcription Start Site

• RNA Polymerase II binds here to begin transcription.

Promoters

• Core Promoter
  • Contains the TATA box sequence (TATAA).
  • A uniform feature across different genes.
  • Binds transcription factors and regulatory proteins to initiate transcription.
• Upstream Promoters
  • Bind proteins that can activate or repress transcription.
  • Differ in number and type among different genes.

Transcription Factors

• Transcription Factor II D (TFIID)
  • Includes TATA binding protein (TBP) that binds to the TATA box.
• Transcription Factor II B (TFIIB)
  • Facilitates the interaction between RNA Polymerase II and TBP.

Enhancers

• Can be located thousands of bases from the gene.
• Enhance transcription by looping around and interacting with promoters.
• Bind special transcription factors to increase transcription rate.

Conclusion

• Understanding these components is essential for grasping how eukaryotic cells regulate gene transcription.
• Further study will delve into the biochemical processes involved in this regulation.