Understanding Eukaryotic Gene Expression Control

1. Regulating Eukaryotic Gene Expression

2. Fig 15.1 • Why change gene expression? • Different cells need different components • Responding to the environment • Replacement of damaged/worn-out parts

3. Two points to keep in mind: • Cellular components are constantly turned-over. • Gene expression takes time: Typically more than an hour from DNA to protein. Most rapidly 15 minutes. Fig 15.1

4. Gene expression can be controlled at many points between DNA and making the final proteins. • Changes in the various steps of gene expression control when and how much of a product are produced. Fig 15.1

5. Gene Expression is controlled at all of these steps: • DNA packaging • Transcription • RNA processing and transport • RNA degradation • Translation • Post-translational Fig 15.1 Fig 16.1

6. Gene Expression is controlled at all of these steps: • DNA packaging • Transcription • RNA processing and transport • RNA degradation • Translation • Post-translational Fig 15.1 Fig 16.1

7. Tightly packaged DNA is unavailable. DNA packaging changes as the need for different genes changes. Fig 10.21

8. Fig 10.21 Different levels of DNA packaging

9. Histones can be post-translationally modified, which affects their abililty to bind DNA.

10. Fig 12.15 Acetylation (-COCH3): post-translational modifications of the histones loosen DNA binding

11. Acetylation of histones (-COCH3) causes a loosening of the DNA/histone bond…unpackaging the DNA.

12. Fig 15.13 DNA methylation

13. DNA methylation often inhibits transcription Fig 15.14

14. Fig 15.15 Epigenetics:the inheritance of DNA modifications, including methylaton

25. Gene Expression is controlled at all of these steps: • DNA packaging • Transcription • RNA processing and transport • RNA degradation • Translation • Post-translational Fig 15.1 Fig 16.1

26. Eukaryotic transcription must be activated by binding of transcription factors Fig 12.14

27. Mutations in the promoter show critical nucleotides

28. Fig 15.12 Enhancers are regulatory regions located some distance away from the promoter

29. Proteins that help bend DNA can play an important role in transcription Fig 15.12

30. Fig 15.12 DNA bends to bring different areas in to close contact.

31. How do eukaryotic cells jointly express several proteins (without operons)?

32. Promoter sequences where transcription factors can bind activating multiple gene in response to the environment

33. Fig 12.13 Promoters typically have several regulatory sequences

34. Steroid response element

35. Fig 15.6 • Steroids bind to receptors/transcription factors inside cell • get translocated to the nucleus • bind to promoters andactivate transcription. cytoplasm

36. Gene Expression is controlled at all of these steps: • DNA packaging • Transcription • RNA processing and transport • RNA degradation • Translation • Post-translational Fig 15.1 Fig 16.1