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1. Introduction
2. Outline
3. Perspective: million fold multiplier
4. Evolutionary and developmental comparisons
5. Phenomenology: stages of mitosis
6. Stages of mitosis (1)
7. Stages of mitosis (2)
8. Primary functions of mitosis
9. Chromosome length and chromosome segregation
10. Lower levels of chromatin organization
11. Two common observations
12. Early whole mount electron microscopy
13. Helical folding at highest level of compaction
14. What we thought we knew
15. Key advance
16. Micrographs of mitotic chromosomes
17. Metaphase chromatid cross section
18. The radial loop model
19. Interpretation
20. SARs and MARs
21. DNA sequences at the base of chromatin loops
22. Nonhistone proteins make up scaffold
23. Sc1 = topoisomerase 2
24. Condensin complex containing Sc2 (1)
25. Condensin complex containing Sc2 (2)
26. Condensin complex containing Sc2 (3)
27. Condensin complex containing Sc2 (4)
28. SMC family of proteins
29. Vindication of radial loop/scaffold model
30. Textbook model: condensation by condensins
31. Challenges to textbook model (1)
32. Challenges to textbook model (2)
33. 200-300 nm subunit in metaphase chromosomes
34. Alternative model - Radial loop, Helical coil model
35. SMC2 gold staining doesn't support the coiling
36. Challenges to the textbook model (3)
37. Topo 2 dependant chromosome condensation
38. Chromosome condensation with topo 2 knockdown
39. Chromosome condensation with SMC2 knockdown
40. What we think we know
41. Phenotype of topo 2 and condensin knockdown
42. Condensins is required for chromosome stability
43. Two condensin complexes are present
44. Condensin 1 versus 2
45. What we'd like to know
46. Chromosome scaffold versus "glue" model
47. Possibilities for condensin knockdown results
48. Condensin activity and chromosome structure
49. Alternative model for chromosome condensation
50. Model
51. Structural studies and chromosome biochemistry
52. Chromosome structure: remaining questions (1)
53. Chromosome structure: remaining questions (2)
54. Recommended reviews

Topics Covered

• Evolutionary and developmental comparisons
• Stages of mitosis
• Primary functions of mitosis
• Lower levels of chromatin organization
• Helical folding
• Experimental foundation of textbook model
• Are there specific DNA sequences at the base of chromatin loops?
• Are there specific nonhistone proteins making up the chromosome scaffold?
• Three independent experimental paths led to identification of condensin complex containing Sc2
• SMC family of proteins
• Condensation by condensins
• Challenges to textbook model
• progressive condensation during prophase
• Alternative model: Radial loop, helical coil model
• What we think we know
• What we'd like to know
• Alternative mechanism for chromosome condensation
• How do we integrate structural studies of chromosome structure with chromosome biochemistry
• We need a better understanding of chromosome structure

Links

Series:

• The Cell Division Cycle

Categories:

• Cell Biology
• Genetics & Epigenetics

Talk Citation

Publication History

• Published on September 3, 2009

Financial Disclosures

• Prof. Andrew Belmont has not informed HSTalks of any commercial/financial relationship that it is appropriate to disclose.