Lecture Notes: Gene Expression and Regulation

Introduction

• Lecture begins with a personal story about an art teacher emphasizing creative expression.
• Transition from creative expression to biological gene expression.

Gene Expression

• Definition: The process by which a gene is used to produce a functional product, often a protein.
• Steps Involved:
  • Transcription: DNA is transcribed into mRNA.
  • Translation: mRNA is translated to form a polypeptide chain, which constitutes a protein.
• Gene Regulation: Not all genes are expressed; regulation is necessary to ensure cells express only the needed genes.

Prokaryotic vs. Eukaryotic Gene Expression

• Prokaryotic Cells:
  • DNA located in cytoplasm; no nucleus.
  • Transcription and translation occur simultaneously.
  • Regulation primarily impacts transcription.
  • Example: Lac Operon controls gene expression via a repressor.
• Eukaryotic Cells:
  • Regulation occurs at multiple stages: transcription, post-transcription, translation, and post-translation.
  • Involves multiple transcription factors and complex regulation mechanisms.

Transcription Factors and Regulation

• Role of Transcription Factors:
  • Bind to promoter regions to initiate or repress transcription.
  • Can also bind to enhancer sequences, even those located far from genes.
  • Environmental factors can influence transcription factors.
• Operons in Prokaryotes: e.g., Lac Operon regulation involves lactose binding to a repressor, enabling transcription.

Eukaryotic Gene Regulation Examples

• Post-Transcription Regulation:
  • mRNA undergoes significant processing; introns are removed.
  • Remaining exons are translated.
• Translation Regulation:
  • Involves initiation factors like eIF-2.
  • Phosphorylation of eIF-2 can halt initiation of translation.
• Post-Translation Regulation:
  • Chemical modifications affect protein function or location.
  • Ubiquitin tagging can lead to protein degradation.

Importance of Gene Regulation

• Implications:
  • Essential for understanding normal cellular function and diseases.
  • Misregulation can lead to diseases like cancer.
  • Gene expression and regulation play significant roles in developing medical treatments.

Conclusion

• Recap of gene expression and its regulation.
• Importance of staying curious in the field of genetics.