Chapter 19 The Organization and Control of Eukaryotic Genomes

1. Chapter 19The Organization and Control of Eukaryotic Genomes

2. Chapter 19The Organization and Control of Eukaryotic Genomes Chromatin structure is based on successive layers of DNA packing.

3. Chapter 19The Organization and Control of Eukaryotic Genomes

4. Chapter 19The Organization and Control of Eukaryotic Genomes

5. Chapter 19The Organization and Control of Eukaryotic Genomes

6. Chapter 19The Organization and Control of Eukaryotic Genomes

7. Chapter 19The Organization and Control of Eukaryotic Genomes

8. Chapter 19The Organization and Control of Eukaryotic Genomes

9. Chapter 19The Organization and Control of Eukaryotic Genomes histone: Protein “beads” that act as a spool for wrapping DNA nucleosomes: Histones, along with their associated DNA.

10. Chapter 19The Organization and Control of Eukaryotic Genomes euchromatin: Extended form of DNA during interphase heterochromatin: Tightly packed DNA in metaphase chromosomes.

11. Chapter 19The Organization and Control of Eukaryotic Genomes Much of the genome is noncoding • Tandemly repetitive DNA (or satellite DNA) is found in telomeres and centromeres • Interspersed repetitive DNA (Alu elements) are found throughout the chromosome.

12. Chapter 19The Organization and Control of Eukaryotic Genomes multigene families: Identical or similar genes clustered together pseudogenes: Very similar to real genes, but code for nonfuctional proteins.

13. Chapter 19The Organization and Control of Eukaryotic Genomes gene amplification: Extra copies of genes for a temporary boost in productivity They exist as tiny circles of DNA in the nucleolus.

14. Chapter 19The Organization and Control of Eukaryotic Genomes transposons: Genes that “jump” from place to place in the genome retrotransposons: Transposons that use an RNA intermediate.

15. Chapter 19The Organization and Control of Eukaryotic Genomes Immunoglobins are proteins that recognize self vs. non-self Immunoglobin genes are permanently rearranged during development (More about this when we study the immune system.)

16. Chapter 19The Organization and Control of Eukaryotic Genomes DNA methylation (adding -CH3 groups) is a way of shutting off certain genes Histone acetylation (adding -COCH3 groups) activates genes This is how cellular differentiation and genomic imprinting work.

17. Chapter 19The Organization and Control of Eukaryotic Genomes Gene expression can be controlled at any step of the process: • DNA unpacking • Transcription • RNA processing • Degradation of RNA • Translation • Polypeptide cleavage and folding • Degradation of protein

18. Chapter 19The Organization and Control of Eukaryotic Genomes Gene expression can be controlled at any step of the process: • DNA unpacking • Transcription • RNA processing • Degradation of RNA • Translation • Polypeptide cleavage and folding • Degradation of protein Regulation is most common at the level of transcription.

19. Chapter 19The Organization and Control of Eukaryotic Genomes control elements: Non-coding DNA that regulates gene expression by binding with transcription factors • Distal control elements (enhancers) • Proximal control elements • Promoter / TATA box.

20. Chapter 19The Organization and Control of Eukaryotic Genomes transcription factors: Proteins that help position RNA polymerase on the DNA • Activators • Repressors.

21. Chapter 19The Organization and Control of Eukaryotic Genomes Eukaryotes do not have operons like the ones in bacteria, but… …coordinately controlled genes, scattered around the genome, share common control elements.

22. Chapter 19The Organization and Control of Eukaryotic Genomes alternate RNA splicing: A single primary transcript can be turned into any one of several different mRNA molecules yourmyhisheranswerisyesnomaybe

23. Chapter 19The Organization and Control of Eukaryotic Genomes alternate RNA splicing: A single primary transcript can be turned into any one of several different mRNA molecules yourmyhisheranswerisyesnomaybe My answer is maybe

24. Chapter 19The Organization and Control of Eukaryotic Genomes alternate RNA splicing: A single primary transcript can be turned into any one of several different mRNA molecules yourmyhisheranswerisyesnomaybe My answer is maybe His answer is no.

25. The Molecular Biology of Cancer protooncogenes: If a mutation makes them too active, they become oncogenes tumor-supressor genes: If a mutation makes them inactive, this can also cause cancer Either kind of mutation will affect regulation of the cell cycle.

26. ras is a proto-oncogene:

27. ras is a proto-oncogene: growth factor

28. ras is a proto-oncogene: growth factor ↓ receptor

29. ras is a proto-oncogene: growth factor ↓ receptor ↓ G protein ras

30. ras is a proto-oncogene: growth factor ↓ receptor ↓ G protein ras ↓ ↓ ↓ transcription factor →

31. ras is a proto-oncogene: growth factor ↓ receptor ↓ G protein ras ↓ ↓ ↓ protein that transcription factor → → stimulates the cell cycle

32. ras is a proto-oncogene: Normal cell division growth factor ↓ receptor ↓ G protein ras ↓ ↓ ↓ protein that transcription factor → → stimulates the cell cycle

33. ras is a proto-oncogene: G protein ras

34. ras is a proto-oncogene: Mutant ras becomes an oncogene: G protein ras

35. ras is a proto-oncogene: Mutant ras becomes an oncogene: G protein ras ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ transcription factor

36. ras is a proto-oncogene: Mutant ras becomes an oncogene: G protein ras ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ transcription factor →

37. ras is a proto-oncogene: Mutant ras becomes an oncogene: G protein ras ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ protein that transcription factor → → stimulates the cell cycle

38. ras is a proto-oncogene: Mutant ras becomes an oncogene: Uncontrolled cell division G protein ras ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ protein that transcription factor → → stimulates the cell cycle

39. P53 is a tumor-supressor gene: growth inhibiting factor

40. P53 is a tumor-supressor gene: growth inhibiting factor ↓ receptor

41. P53 is a tumor-supressor gene: growth inhibiting factor ↓ receptor ↓ G protein

42. P53 is a tumor-supressor gene: growth inhibiting factor ↓ receptor ↓ G protein ↓ ↓ ↓ p53 transcription factor →

43. P53 is a tumor-supressor gene: growth inhibiting factor ↓ receptor ↓ G protein ↓ ↓ ↓ p53 protein that transcription factor → → stops the cell cycle

44. Mutation in the p53 gene: growth inhibiting factor ↓ receptor ↓ G protein ↓ ↓ ↓ p53 protein that transcription factor →(defective) → stops the cell cycle

45. Mutation in the p53 gene: growth inhibiting factor ↓ receptor ↓ G protein ↓ ↓ ↓ p53 defective protein transcription factor → (defective) → does not stop the cell cycle

46. Mutation in the p53 gene: growth inhibiting factor ↓ receptor ↓ G protein ↓ ↓ ↓ p53 defective protein transcription factor → (defective) → does not stop the cell cycle

47. The Molecular Biology of Cancer Most cancers involve multiple mutations • Some of these can be inherited • This is why a predisposition to some types of cancer runs in families.

48. The Molecular Biology of Cancer p53 is a damage control protein • It stimulates DNA repair • It halts cell division • It can trigger apoptosis (cellular suicide.) .