1. Journal: What is mitosis? Why is it important?
January 19, 2017
Journal: What is mitosis? Why is it important?
Hand in your homework

2. The Cell Cycle

3. The Cell Cycle Four Phases G1 – Gap 1 S – DNA Replication G2 – Gap 2
Mitosis

4. Interphase Occurs when the cell is not dividing
Cells spend the majority of their time in this phase
Made up of three phases
G1 – Growth Phase
S – DNA Replication Occurs
G2 – Growth Phase

5. Mitosis Division of the nucleus Occurs in 4 stages: PMAT
Prophase
Metaphase
Anaphase
Telophase

6. 1st: Prophase
The nuclear membrane disappears

7. 2nd: Metaphase
Pairs of chromosomes line up at the center of the cell

8. 3rd: Anaphase
Pairs of chromosomes separate and begin to move to opposite ends of the cell

9. 4th: Telophase Two new nuclei form around the chromosomes
Chromosomes become chromatin (threads rather than X’s)
Mitosis ends

10. Cytokinesis Last stage of the cell cycle
Not part of mitosis
Cell membrane pinches inwards to create two daughter cells – each with its own nucleus with identical chromosomes

11. How long does the cell cycle take?

12. How is the cell cycle regulated?
Cyclins – proteins that regulate the amount of time spent at each stage of the cell cycle

13. Checkpoints
At the end of each stage cells must pass through checkpoints to make sure that the cell is at the appropriate point in the cell cycle
If not, the cell will be destroyed
When cells that should not pass through the checkpoint do anyway it results in cancer

14. What is cancer?
Cancer is the uncontrolled cell growth of abnormal cells in the body.

15. How does cancer occur?
Step 1: External factors cause mutations in the DNA
Can be genetic or caused by carcinogens (cancer causing agents)
Step 2: Cell loses its ability to control it’s grow and division
Step 3: Over an extended period of time, a mass of cells known as a tumor will form

16. Formation of Tumors

17. Types of Tumors Slow growing and does not metastasize Malignant Tumors
Fast growing
Likely to metastasize (spread to other parts of the body and cause problems)
Benign Tumors
Slow growing and does not metastasize