1. The Cell Cycle

2. How long do the cells in your body live?
Question
How long do the cells in your body live?

3. Answer
It depends.

4. Answer Different cells live for different lengths of time.
For example, here’s how often some different kinds of cell need to be replaced.

5. Answer Skins cells – 20 days Liver cells – 200 days
Brain cells – 30 – 50 years
Intestinal lining – 3 days
Stomach lining – 2 days
Red blood cells – 120 days

6. If cells have such a short life-span, and you are made of cells, this must mean that A LOT of cells are dying all the time.

7. If cells have such a short life-span, and you are made of cells, this must mean that A LOT of cells are dying all the time.
In fact, about 300 million of your cells die each minute.

8. This must also mean that A LOT of cells are being produced to replace the ones that are lost.

9. Cells are produced as part of THE CELL CYCLE

10. The Cell Cycle
So, how do we replace all those cells that we lose everyday?

11. The Cell Cycle
So, how do we replace all those cells that we lose everyday? Cell Division

12. The Cell Cycle
Most of the cells in your body replace themselves in a process called
MITOSIS

14. The Cell Cycle
The cell cycle is divided into three stages

15. The Cell Cycle Interphase Mitosis Cytokinesis
The cell cycle is divided into three stages
Interphase
Mitosis
Cytokinesis

16. The Cell Cycle
Interphase is the longest stage in the cells life. It is when a cell carries out its various functions within the organism.
During interphase cells
Grow in size
Prepare for cell division
Replicate their DNA

18. DNA Replication DNA makes a copy or “replica” of itself during
interphase.
So for a little while the
cell has 2 complete
sets of DNA.

19. DNA Replication

20. Mitosis
Mitosis is the next stage in the cell cycle. (But a lot of things happen.)
Mitosis is divided into 4 phases.
Prophase
Metaphase
Anaphase
Telophase

21. Mitosis

22. The Cell Cycle The last stage of the cell cycle is Cytokinesis.
This is when the original (parent) cell separates into to new (daughter) cells

23. The Cell Cycle - Review
A single cell divides to make two new cells – this is how our body replaces cells.
Most of the cells in our body do this with a process called MITOSIS.

24. The Cell Cycle - Review
Before mitosis can occur the DNA in the cell must Replicate. This happens during Interphase.
Mitosis results in two new cells that are IDENTICAL to the original parent cell.