1. Mitosis
H Biology

2. What is Mitosis?
Mitosis is the process where cells divide to produce new cells
Occurs in healing, growth, and day-to-day life
Ex: Hair growth, nail growth, wound healing…
ALL eukaryotic organisms produce new cells through mitosis

3. Cell Cycle Consists of 2 main stages:
1. Interphase – the “growing” stage
2. Mitotic Phase – Cell Division

4. Interphase
The majority of the cell cycle (90%) is spent in Interphase prior to Mitosis
Interphase is divided into 3 sub sub-phases:
G1 Phase
S Phase
G2 Phase

5. G1 Phase
Cell begins to grow  needs to increase its surface area before dividing
Why?
Growth continues through S Phase
Organelles increase in number and size
Chromosomes appear as threadlike coils
Made of Chromatin, a combination of DNA and protein molecules
In G1, cells accomplish most of their growth; they get bigger in size and make proteins and organelles needed for normal functions of DNA synthesis. Here, proteins and RNAs are synthesized, and, more especially the centromere and the other components of the centrosomes are made. The cells are fully functional

6. S Phase (Synthesis) “Synthesis” = To Make
During the S Phase, DNA is replicated
Chromosomes are copied (# doubles)
The region where the two chromatids are joined tightly together is called the centromere.
Growth continues
Each chromosome is single  replication occurs and then the chromosomes are doubled each consisting of two sister chromatids
Chromatin doubles

7. G2 Phase
Cell size continues to increase and prepares for cell division
At the end of this phase, there is double the amount of DNA, centrioles have replicated, and the cell is big enough for cell division.

8. Interphase Recap ✔ ✔ ✔
Up Next 

9. Mitotic Phase After Interphase, comes the Mitotic Phase begins.
Two parts:
Mitosis
Cytokinesis
Cytokinesis usually begins before Mitosis is completed.

10. Mitosis
During mitosis, the nucleus and doubled chromosomes divide  create two identical daughter cells
4 sub phases:
Prophase
Metaphase
Anaphase
Telophase
Prophase (pro- means before)
Metaphase (meta- means middle)
Anaphase (ana- means without)
Telophase (telo- means end)
Cytokinesis usually begins before Mitosis is completed.

11. Prophase First phase of Mitosis: Nuclear envelope breaks down
Chromatin fibers condense,
becoming the compact structure
we call a chromosome.
Spindles (made by the
centrioles) begins to
form in the cytoplasm
Centrioles
Spindles
92 chromosomes of DNA at this point

12. Prophase
2. Centrioles move
DNA supercoils into chromosomes

13. Metaphase Second phase of Mitosis: Nuclear membrane disappears
Chromosomes attach to the spindle at the centromeres
Chromosomes line up in the middle of the cell forming an equator
92 chromosomes at this point

14. Metaphase

15. Anaphase Third phase of Mitosis:
Spindle pulls apart chromosomes (by an attachment to the centromere)
Chromatids separate at the centromere and move towards each end
Each chromatid is now
considered its own
chromosome
Still 92 chromosomes….

16. Anaphase

17. Telophase Fourth (and final) phase of Mitosis:
Chromosomes reach end of spindle
Spindle breaks down
Cleavage furrow begins to form
Nuclear membrane begins to reform
NOW each cell has 46 chromosomes (23 pairs)

18. Telophase
Spindle fall apart
Cleavage furrow

19. Cytokinesis Second part of the Mitotic Phase
Cleavage furrow pinches all the way through
The cytoplasm is divided in two
DNA uncoils into chromatin again
Result is two new cells
Officially 2 new cells with 46 chromosomes EACH

20. And the Cycle Continues…
2 NEW cells then enter the cycle and Mitosis begins again! YAY!
G1, S, G2 (Interphase)
PMAT & Cytokinesis
Each new cell at the end of mitosis is DIPLOID
Has a full set of chromosomes (46)

21. IPMATC Interphase Prophase Metaphase Anaphase Telophase Cytokinesis
I Play Monopoly At Camp

22. Recap

23. What is Apoptosis? Apoptosis is controlled, programmed cell death
This is how we develop fingers (instead of having a webbed hand) and how women menstruate
This is very important for maintaining healthy, functioning cells within our body!
However, sometimes apoptosis doesn’t happen  cancer
When a cell is compelled to commit suicide proteins called caspases go into action. They break down the cellular components needed for survival, and they spur production of enzymes known as DNases, which destroy the DNA in the nucleus of the cell. It's like roadies breaking down the stage in an arena after a major band has been through town. The cell shrinks and sends out distress signals, which are answered by vacuum cleaners known as macrophages. The macrophages clean away the shrunken cells, leaving no trace, so these cells have no chance to cause the damage that necrotic cells do.

24. What is Cancer? Disease caused uncontrollable cell division
Can spread cancer cells throughout the body
METASTASIS
Cancer “masses” displaces normal tissue

26. What are the treatments for cancer?
Surgery
Radiation Therapy
High energy radiation disrupts cell division
Chemotherapy
Drugs disrupt cell division
Anti-mitotic drug freezes spindle fibers