1. Cell Cycleand Mitosis!Cell Cycleand Mitosis!

2. Review  Why do cells divide?? Big cells are inefficient! Nutrients can’t reach the organelles! Proteins can’t be synthesized quickly enough! Volume increases much faster than surface area!

3. Before Cells Divide… INTERPHASE! INTERPHASE! – Cells carry out normal functions – Most of a cell’s time is spent in this phase – 3 parts!  G 1, S, and G 2

4. G 1 PHASE DNA stored as chromatin  loose and unwound Cell grows and organelles replicate SPHASE Synthesis DNA replicates G 2 PHASE Rapid growth before division

5. INTERPHASE

6. Now the cell is ready to divide! MITOSIS: The division of the nucleus! 4 Phases!

7. PROPHASE DNA condenses into chromosomes Nucleus disappears Spindle fibers form Centrioles move to side

8. PROPHASE:

9. METAPHASE Chromosomes line up down the middle of the cell Spindle fibers attach to centromere

10. METAPHASE

11. ANAPHASE Chromatids separate Spindle fibers pull chromosomes to the sides

12. ANAPHASE

13. TELOPHASE Cleavage Furrow forms Nucleus reforms DNA unravels Centrioles and spindle fibers disappear

14. TELOPHASE

15. Quick Mitosis Summary… Mitosis  Division of the nucleus – 1 Prophase – 2 Metaphase – 3 Anaphase – 4 Telophase – Ready for the last part of the cell cycle???

16. CYTOKINESIS! Division of the cytoplasm Cell splits into 2 new cells! NOT a part of mitosis Cell Plate Cleavage Furrow

17. The Cell Cycle!

18. The Cell Cycle: