Chapter 10-2

1. CELL DIVISION Chapter 10-2

2. CELL DIVISION • Chromosomes are not visible in cells until cells begin the process of cell division.

3. CELL DIVISION • Chromosomes consist of two identical sister chromatids.

4. CELL DIVISION • A centromere holds the two sister chromatids together at their centers.

5. CELL DIVISION • Cell Cycle • The cell goes through a stage called interphase between cell divisions.

6. The Cell Cycle • Cells grow and then divide in a series of events called the cell cycle.

7. The Cell Cycle

8. The Cell Cycle • M phase is the when the nucleus divides.

9. The Cell Cycle • Interphase consists of: • G1 phase • S phase • G2 phase

10. The Cell Cycle • G1 phase - cells do most of their growing.

11. The Cell Cycle • S phase

12. The Cell Cycle • G2 phase

13. Mitosis • Four phases: • Prophase • Metaphase • Anaphase • Telophase

14. Mitosis • Centrioles are the tiny structures located in the cytoplasm near the nuclear envelope at the beginning of prophase.

15. Mitosis • Spindle – is the fanlike microtuble structure that helps separate the chromosomes.

16. Mitosis • During Prophase: • the chromosomes become visible in the nucleus; • the centrioles take up positions on opposite sides of the nucleus.

17. Mitosis • During Metaphase: • The chromosomes line up in the center of the cell.

18. Mitosis • During Anaphase : • The chromosomes move until they form two separate • Forming groups at opposite poles of the spindle.

19. Mitosis • During Telophase: • the nuclear envelope re-forms around each cluster of chromosomes; • the nucleolus becomes visible in each daughter nucleus.

20. Cytokinesis • Cytokinesis is the division of the cytoplasm.

21. Cytokinesis • How does it happen in animals? • The membrane is drawn downward until it is pinched into nearly two equal parts.

22. Cytokinesis • A cell plate is formed midway between the divided nucleus during cytokinesis in plant cells.