1. Stages of the
Cell cycle

2. The Life of a Cell An organized sequence of growing until it divides
One cell divided into 2 “daughter cells”

3. Why Divide? Single celled organisms For multicellular organisms
For reproduction
For multicellular organisms
For development from fertilized egg to adult
For growth and repair

4. Cell Cycle 2 major periods: Interphase Cell division
Period of growth in-between divisions
Cell division
Period during which cell splits in 2

5. Interphase – Part I G1 Phase Period of growth Cell increases in size
Cell makes new proteins and organelles

6. Interphase – Part II S Phase Synthesis of DNA molecules
Chromosomes replicated

7. Interphase – Part III G2 Phase Preparation for cell division
Organelles and molecules necessary for division are produced

8. Cell in Interphase

9. On to the next part…

10. Cell Division The period of cell division is also called M Phase
2 major periods:
Mitosis
Process of cell’s nucleus dividing
Cytokinesis
Process of entire cell dividing

11. M Phase - Mitosis 4 major periods Prophase Metaphase Anaphase
Telophase

12. M Phase – Mitosis – Part I
Prophase
Chromatin begins to condense into chromosomes
Centrioles separate on opposite sides of nucleus
Spindle fibers form and approach centromeres
Nuclear envelope breaks down

13. M Phase – Mitosis – Part I
Prophase

14. M Phase – Mitosis – Part II
Metaphase
Spindle fibers
attach to each
chromosome at
the kinetochore
Chromosomes
line up across
center of cell

15. M Phase – Mitosis – Part II
Metaphase

16. M Phase – Mitosis – Part III
Anaphase
Sister chromatids split and are pulled apart by spindle toward opposite ends

17. M Phase – Mitosis – Part III
Anaphase

18. M Phase – Mitosis – Part IV
Telophase
Chromosomes begin to untangle back into chromatin
Nuclear envelope reforms around each cluster of genetic material
Spindle breaks apart

19. M Phase – Mitosis – Part IV
Telophase

20. M Phase – Cytokinesis
Cell membrane drawn in until cytoplasm pinched into 2 equal parts

21. M Phase – Cytokinesis
Animal cells: contractile ring pinches cell membrane forming cleavage furrow

22. M Phase – Cytokinesis
Plant cells: cytoplasm divided by cell plate which develops into cell membrane and cell wall

23. Put it all Together…