Eukaryotic Gene Regulation

Key Notes when i go home to Knotes or wtv can u take a picture of your profile so i can find it? also in the bio gc they shared notes so ONCE THEY FREAKING LOAD i’ll send them to you, too.

What You Will Learn

• How transcription is regulated in eukaryotes

• The role of regulatory elements in gene regulation

• The importance of gene expression regulation during development

• How cancer develops due to altered gene regulation

Eukaryotic Gene Regulation

• More complex than in prokaryotes, involving many proteins and regulatory elements

• Enhancers are distant DNA regions that loop back to interact with the promoter

• Regulatory proteins control transcription by binding to DNA or to each other

The TATA Box

• A common regulatory element in the promoter of most eukaryotic genes

• Has a TATAAA core sequence

• Binds multiple regulatory proteins, forming a complex recognized by RNA polymerase

• Transcription starts only when all necessary proteins are bound

Gene Regulation During Development

• Essential for proper organ and body formation

• Homeobox genes (hox genes) are regulatory genes that control the activation of developmental genes

• Mutations in hox genes can lead to major developmental defects (e.g., legs growing where antennae should be in fruit flies)

Gene Expression and Cancer

• Cancer occurs when mutations disrupt regulatory genes controlling the cell cycle

• Two key types of genes involved:

  • Tumor-suppressor genes: Normally inhibit cell division; mutations cause uncontrolled growth

  • Proto-oncogenes: Normally stimulate cell division when needed; mutations turn them into oncogenes, causing excessive division

• Mutations in these genes lead to rapid, uncontrolled cell growth → tumor formation and cancer

Summary

• Eukaryotic transcription regulation is more complex than in prokaryotes

• The TATA box is a key promoter sequence in transcription

• Homeobox genes regulate development by switching genes on/off

• Mutations in regulatory genes can lead to cancer

Review Questions

1. Identify the TATA box and its function in transcription.

2. What is a homeobox gene?

3. Why is gene regulation especially important during development?

4. What are tumor-suppressor genes and proto-oncogenes?

5. Sketch an insect with a mutated hox gene and explain the mutation's effect.