1. Today we’re going to talk about…
The
Cell Cycle!

2. What is the Cell Cycle?
The events a cell goes through as it grows and divides
What are the 5 phases of the cell cycle?
First Growth Phase (G1)
Synthesis Phase (S)
Second Growth Phase (G2)
Mitosis
Cytokinesis

3. The Cell Cycle
90% of cell’s time spent in three stages that are collectively called Interphase
During interphase, cells:
1. Make ATP.
2. Repair themselves.
3. Excrete their waste.
4. Grow in size.
5. Carry on metabolism.
6. Duplicate their chromosomes.

4. G1 phase
G2 phase
S phase
Cell grows rapidly while carrying out routine functions
The cell’s DNA is copied during this phase – REPLICATION!
Preparation for mitosis
DNA checked for errors.

5. The cell would begin mitosis…
After G1, S, and G2 Phases…
The cell would begin mitosis…

6. Phases of Mitosis There are four distinct phases of mitosis. Prophase
Metaphase
Anaphase
Telophase

7. Phases of Mitosis- PROPHASE
Chromatin becomes chromosomes.
Nucleus begins to disappear.
Centrioles begin to move to opposite ends.
The spindle begins to form between the centrioles.

8. Phases of Mitosis-METAPHASE
Chromosomes become attached to the spindle fibers by their centromeres.
The chomosomes begin to line up in the midline of the spindle with each chromatid attached to a separate spindle fiber by its centromere.

9. Phases of Mitosis- ANAPHASE
Centromeres split and sister chromatids are pulled apart to opposite poles of the cell.
Each chromatid is now a separate chromosome.

10. Phases of Mitosis-TELOPHASE
Two daughter cells are formed.
The nucleolus and nuclear envelope reappear, and the chromosomes begin to uncoil.

11. Cytokinesis: division of the cytoplasm
After mitosis, two nuclei are formed
Cell membrane grows to enclose each cell
Forming two genetically identical cells

12. Cytokinesis is different in plant and animal cells.
Animal cells form a cleavage furrow…..
Plant cells form a cell plate…

13. Now let’s watch a cell divide…
Results of Mitosis
Mitosis guarantees genetic continuity by the production of two new identical cells.
The new cells carry out the same cellular processes and functions as those of the parent cell.
Now let’s watch a cell divide…

15. Mitosis Animation
This animation is a review of mitosis. Have students review what is happening to the chromosomes.
Animation from

16. Control of the Cell Cycle
Cells have “red light-green light” switches that turn cell division on and off…

17. These switches are called “checkpoints”
G1 Checkpoint- Is the cell healthy enough and large enough for division?
G2 Checkpoint- Checks DNA replication for errors and repairs occur if necessary.
Mitosis Checkpoint- triggers exit from mitosis and beginning of G1 phase.

18. CYCLINS
Proteins that regulate the timing of the cell cycle in eukaryotic cells.