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Chapter 12

Chapter 12. The Cell Cycle. 100 µm. Figure 12.2 A. Key Roles of Cell Division. Unicellular organisms Reproduce by cell division. 200 µm. 20 µm. (c) Tissue renewal. Bone marrow cells. (b) Growth and development. Figure 12.2 B, C. Key Roles of Cell Division. Multicellular organisms

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Chapter 12

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  1. Chapter 12 The Cell Cycle

  2. 100 µm Figure 12.2 A Key Roles of Cell Division • Unicellular organisms • Reproduce by cell division

  3. 200 µm 20 µm (c) Tissue renewal. Bone marrow cells (b) Growth and development. Figure 12.2 B, C Key Roles of Cell Division • Multicellular organisms • Development from a fertilized cell • Growth • Repair

  4. Concept 12.1 • How does Cell division results in genetically identical daughter cells?

  5. Concept 12.1 • How does Cell division results in genetically identical daughter cells? • Cells duplicate their genetic material before they divide

  6. 50 µm • A cell’s DNA = Genome Genome Chromosomes DNA molecule and proteins (Chromatin) Genes

  7. Cell not dividing = • Chromosomes thin, loosely packed fibers called chromatin

  8. Cell not dividing = • Chromosomes thin, loosely packed fibers called chromatin • Cell dividing = • Individual Chromosomes visible

  9. Before a cell divides chromosomes replicate = sister chromatids joined together at the centromere Figure 8.4B

  10. Before a cell divides chromosomes replicate = sister chromatids joined together at the centromere Figure 8.4B

  11. Before a cell divides chromosomes replicate = sister chromatids joined together at the centromere Figure 8.4B

  12. During Cell division sister chromatids separate • 2 daughter cellseach contain a complete, identical set of chromosomes Figure 8.4C

  13. The cell cycle 2 major phases- Interphase and Mitotic Figure 8.5

  14. Interphase- 3 subphases • G1 phase • S phase • G2 phase Figure 8.5

  15. What Happens During Each Phase? • Interphase • Cell parts are made (G1, G2 phase) • Chromosomes duplicate (S phase) • Mitotic phase • Duplicated chromosomes separate • Separated chromosomes are distributed into two daughter cells

  16. Interphase + Mitotic Phase = Cell cycle: • Interphase • Prophase • Metaphase • Anaphase • Telophase • Cytokinesis

  17. The 5 stages of cell division • Interphase: • - Cell growth • Chromosomes condense • Chromosomes duplicate • Nuclear envelope begins to breakdown Figure 8.6 (Part 1)

  18. The stages of cell division • Prophase: • Duplicated Chromosomes appear as 2 sister chromatids connected at the centromere • - Mitotic spindle forms in cytoplasm from centrosomes Figure 8.6 (Part 1)

  19. The stages of cell division • Metaphase: • Mitotic spindle fully formed • Duplicated Chromosomes line up on metaphase plate located in middle of the cell • Each sister chromatid is attached to a spindle fiber Figure 8.6 (Part 1)

  20. The stages of cell division • Anaphase: • Sister chromatids are pulled apart and taken to opposite poles of the cell by the spindle fibers • Cell elongates Figure 8.6 (Part 1)

  21. Telophase: • Roughly opposite prophase: • Nuclear envelopes begin to reform around chromosomes • Chromosomes begin to uncoil • Mitotic spindle disappears • Mitosis complete! • The stages of cell division

  22. Cytokinesis: -Division of the cytoplasm -Animals = cleavage furrow • The stages of cell division

  23. Cytokinesis differs for plant and animal cells • Animals • Cytokinesis occurs by a constriction of the cell (cleavage) Figure 8.7A

  24. Plants • membranous cell plate (golgi vesicles) forms and splits the cell in two Figure 8.7B

  25. What Phase of Mitosis?

  26. What Phase of Mitosis?

  27. 8.11 Review: stages of mitosis Figure 8.11A

  28. 0 • A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 8 picograms of DNA per nucleus. Those cells would have __________ picograms at the end of the S phase and __________picograms at the end of G2. A 8 ... 8 B 8 ... 16 C 16 ... 8 D 16 ... 16 E 12 ... 16

  29. The Mitotic Spindle: A Closer Look • The mitotic spindle • Is an apparatus of microtubules that controls chromosome movement during mitosis

  30. The Spindle • Centrosomes • Spindle microtubules • Asters

  31. How are chromosomes pulled to poles? 1 1

  32. How are chromosomes pulled to poles?

  33. How are chromosomes pulled to poles?

  34. How are chromosomes pulled to poles?

  35. ? 0 • Cytokinesis usually, but not always, follows mitosis. If a cell completed mitosis but not cytokinesis, what would be the result? A a cell with a single large nucleus B a cell with high concentrations of actinand myosin C a cell with two abnormally small nuclei D a cell with two nuclei E a cell with two nuclei but with half theamount of DNA

  36. Binary Fission: Prokaryotes (bacteria) • Origin of replication = duplicated

  37. Binary Fission Prokaryotes (bacteria) • Origin of replication = duplicated • One copy of origin moves to opposite end

  38. Binary Fission Prokaryotes (bacteria) • Origin of replication = duplicated • One copy of origin moves to opposite end • Replication continues; cell elongates

  39. Review • Interphase + Mitotic phase = Cell division in Eukaryotes • Binary Fission- Cell division in Prokaryotes • Similarities and Differences? • Mitotic Spindle- How do sisters move to poles?

  40. How are chromosomes pulled to poles? 1 1

  41. How are chromosomes pulled to poles?

  42. How are chromosomes pulled to poles?

  43. How are chromosomes pulled to poles?

  44. Concept 12.3 How is cell cycle is regulated ? = Molecular control system - Controls frequency of cell division - Ex: Skin vs. muscle cells

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