Lecture on Gene Expression and Regulation

Introduction

• Personal anecdote about art teacher emphasizing self-expression.
• Initial misunderstanding of expression, later understood as creativity and gene expression.

Gene Expression

• Definition: Gene expression involves using a gene to make something functional, often a protein.
• Process:
  • Transcription: DNA transcribed into mRNA.
  • Translation: mRNA used to create polypeptide chains, forming proteins.
• Not all genes are expressed; expression is regulated.
• Importance of gene regulation in cells to prevent wasteful or unnecessary protein production.

Differences in Gene Regulation

• Prokaryotic Cells:
  • DNA in the cytoplasm, no nucleus.
  • Transcription and translation can occur simultaneously.
  • Regulation often impacts transcription directly.
• Eukaryotic Cells:
  • DNA within a nucleus.
  • Multiple stages for gene regulation: transcription, post-transcription, translation, and post-translation.

Transcription and Regulation

• Transcription Factors:
  • Proteins that increase or decrease transcription.
  • Bind to promoter regions to assist or repress RNA polymerase.
  • Can bind to enhancer sequences to increase transcription.
• Environmental Influence: External factors can affect transcription factors and thus gene expression.

Prokaryotic Gene Regulation Example: Lac Operon

• Lac Operon:
  • Repressor blocks RNA polymerase.
  • Presence of lactose removes repressor, allowing transcription and protein production.
  • Example of gene expression based on environmental need.

Epigenetics and Regulation

• Epigenetic Marks:
  • Chemical modifications (e.g., methyl groups) affect DNA packing.
  • Tightly packed DNA restricts transcription factor access, inhibiting transcription.

Eukaryotic Gene Regulation

• Post-Transcription:
  • mRNA processing, introns removed, exons remain for translation.
• Translation Regulation:
  • eIF-2 protein helps initiate translation; can be inhibited by phosphorylation.
• Post-Translation Regulation:
  • Chemical modifications affect protein location and function.
  • Ubiquitin: Signals protein degradation.

Importance of Gene Regulation

• Understanding gene expression is key to understanding cellular functions and malfunctions.
• Misregulation can lead to diseases such as cancer.
• Gene regulation is crucial for developing medical treatments.

Conclusion

• Summary of gene expression and regulation.
• Encouragement to remain curious.

Note: This content covered by "Amoeba Sisters" as part of educational series.