1. The Cell Cycle and Mitosis

2. Why Do Cells Divide?

3. Why Do Cells Divide Healing and Tissue Repair
An average human looses 105 pounds of dead skin cells in their life
Every second, millions of your body cells are injured or die and must be replaced
Replacement of dead cells also occurs in plants

4. Why Do Cells Divide Growth
All plants and animals begin life as a single cell
Only two ways for an organism to grow: 1) single cell gets bigger; or 2) the single cell divides into more cells

5. Why Do Cells Divide
One of the most important jobs of a cell is to exchange materials with its environment (the body or outside world)
The cell needs to get food and nutrients in and waste out

6. Why Do Cells Divide Why Don’t Cells Just Keep Getting Bigger?
Eventually a cell will reach a size where it will not be able to get enough exchange of materials to sustain cell function

7. Why Do Cells Divide Perpetuate Life
Important for unicellular (prokaryotes) organisms like bacteria – creates 2 new organisms

8. Why Do Cells Divide Perpetuate Life
Also essential for reproduction of multicellular organisms

9. The Cell Cycle The repeating cycle in the life of a cell
Interphase : when a cell is preparing for cell division; this is the majority of the time
Cell division : the process of 1 cell dividing into 2 cells
Mitosis: division of the nucleus
Cytokinesis : division of the cytoplasm

11. Interphase First Growth Phase (G1) Synthesis Phase (S)
Period of growth for a cell
Produces new proteins and organelles
Synthesis Phase (S)
Cell synthesizes entire copy of DNA
Second Growth Phase (G2) – shortest phase
Cell produces organelles and structures for cell division

12. Mitosis: What is it basically?
DNA copies (chromosomes) are separated & sorted into two sides of the cell
the cell then splits in two and part of each parent is carried to the two new cells.
each ‘daughter’ cell is identical to the parent cell
results in cells such as internal organs, skin, bones, blood, etc.
Mitosis animation:

13. Interphase occurs just before Mitosis begins:
DNA is replicated along with organelles and other cellular components and the cell prepares for division.

14. Before Mitosis : Interphase
Animal cell
Plant cell
Photographs from:

15. 1st step in Mitosis: Prophase (preparation phase)
the DNA recoils, and the chromosomes condense
the nuclear membrane disappears
mitotic spindles begin to form.

16. Mitosis Prophase Animal cell Plant cell
Photographs from:

17. 2nd step in Mitosis: Metaphase (organizational phase)
spindle fibres attach to the chromosomes at the centromere
chromosomes line up the middle of the cell

18. Mitosis Metaphase Animal cell Plant cell
Photographs from:

19. 3rd step in Mitosis: Anaphase (separation phase)
the chromosomes split at the centromere
the ‘sister ‘chromatids are pulled by the spindle fibers to opposite poles of the cell.

20. Mitosis Anaphase Animal cell Plant cell
Photographs from:

21. 4th step in Mitosis: Telophase
the chromosomes, the cytoplasm and organelles divide into 2 portions. 
this diagram shows the end of telophase.

22. Mitosis Telophase Animal cell Plant cell
Photographs from:

23. After Mitosis: Cytokinesis
Beginning of cytokinesis in a plant:
the actual splitting of the daughter cells into two separate cells is called cytokinesis
occurs differently in
both plant and animal
cells.
Beginning of cytokinesis in an animal:

24. MITOSIS

25. Mitosis http://www.youtube.com/watch?v=2WwIKdyBN_s&feature=related
Beginning of second class

27. The Cell Cycle Remember iPMATc Interphase Mitosis Cytokinesis Prophase
Metaphase
Anaphase
Telophase
Cytokinesis

28. Homework Describe the events in the cell cycle.
Explain how mitosis ensures genetic continuity.
How does mitosis make the growth and repair of cells possible in an organism?
Get a textbook and describe each phase of mitosis along with a picture (pg )
Also define cytokinesis and apoptosis