1. Ch 5 and 6.1 and 6.2
Cell Division

2. Cell Reproduction Mitosis Meiosis Creates 2 Creates 4 identical cells
different cells
Creates body cells
Creates sex cells
Diploid cells = 2n or
2 sets of chromosomes
Haploid cells = 1n or
1 set of chromosomes
Body cells, Skin Cells, Tissues, Organs
Sperm and egg

3. Mitosis Why do cells reproduce? GROWTH REPAIR
Increase in number of cells.
GROWTH
____________________
Replace worn out or damaged cells.
REPAIR
____________________

4. Life Spans of
Body Cells

5. The cell cycle has four main stages.
1. Gap 1: Cell Growth
2. Synthesis: DNA Replication
3. Gap 2: Preparation of Mitosis
4. Mitosis
Interphase – A long period of cell growth

6. G1 Phase: The cell grows in size.
Checkpoint 1
S Phase:
DNA # is
doubled.
Checkpoint 2
G2 Phase: gets ready for mitosis. Develops its organelles.
*Has 2 complete sets of DNA

7. Interphase
G1 phase: Cell Growth
S phase: DNA Replication

8. Duplicated Chromosome = Sister chromatids
1 Chromosome = 1 chromatid
Duplicated Chromosome = Sister chromatids

9. Condensed, duplicated chromosome or sister chromatids
centromere
Condensed, duplicated chromosome or sister chromatids
Holds the duplicated chromosome together
G2 phase: Cell gets ready for mitosis

10. ***DNA is in the form of Chromatin (ball of DNA)
INTERPHASE
***DNA is in the form of Chromatin (ball of DNA)
Centrioles copies are made
1. More cytoplasm- cell grows.
2. DNA is being replicated.
3. More organelles
The cell is getting ready for MITOSIS, cell division.

11. _______________________________________
Steps of Mitosis
Prophase
Metaphase
Anaphase
Telophase
_______________________________________
PMAT

12. X 3. Centrioles move apart. 2. Nuclear Membrane Breaks down
Mitosis – PROPHASE
4. Fibers form
3. Centrioles move apart. X
1.Chromatin forms visible chromosomes
2. Nuclear Membrane Breaks down

13. PROPHASE 1. DNA 2. Nuclear Membrane 3. Centrioles 4. Fibers
Move apart from one another in opposite directions
Begins to break down
Form between centrioles
Chromatin condenses into visible chromosomes

14. 4.THE NUCLEAR MEMBRANE IS NO LONGER PRESENT
2. Spindle fibers connect to the sister chromatids
Mitosis – Metaphase
4.THE NUCLEAR MEMBRANE IS NO LONGER PRESENT X
3. Sister chromatids are lined up along the middle of the cell.
1. Centrioles move to opposite poles.

15. METAPHASE 1. Centrioles 2. Fibers 3. DNA 4. Nuclear Membrane
Sister chromatids are pulled to the middle of the cell
Continue to move to opposite ends of the cell
Attach to the sister chromatids.
Is completely gone

16. Mitosis – ANAPHASE
2.Centrioles begin to pull the chromosomes toward the opposite sides of the cell.
>
1. Sister Chromatids separate

17. ANAPHASE 1.Sister Chromatids 2.Fibers 3.Centrioles 4.Nuclear Membrane
Pulled apart
Each chromatid is separate from its “sister”
Still at opposite sides of the cell
Pull each chromatid toward opposite ends of cell
Is still gone

18. > 2. Nuclear Membrane begins to reappear
Mitosis – TELOPHASE
>
2. Nuclear Membrane
begins to reappear
3.Cell Membrane pinches at center
4. Fibers begin to disappear
1.Chromosomes are at opposite sides of the cell

19. TELOPHASE 1.Sister Chromatids 2.Nuclear Membrane 3.Cell Membrane
4.Fibers
Each end of cell has a complete set of chromosomes.
Begins to pinch at the center, forming two new identical cells
Begin to disappear
Begins to reform around the sets of chromosomes

20. Cell Membrane splits into two new identical cells
CYTOKINESIS
Cell Membrane splits into two new identical cells

21. METAPHASE
PROPHASE
TELOPHASE
ANAPHASE
Cytokinesis

22. ANAPHASE METAPHASE TELOPHASE PROPHASE Phases of Mitosis: Prophase

23. So What Does The Process of Mitosis Look Like? Another Animation
Control of the
cell cycle
Cell Cycle of Mitosis
Interactive review
of mitosis from
Classzone.com
Video clips

24. Plant Cell vs. Animal Cell
MITOSIS
Plant Cell vs. Animal Cell
The process is VERY SIMILAR in each type of cell.
There are only 2 differences:
Plant cells do not have centrioles
The cell membrane cannot pinch because of the cell wall.
Instead a cell plate forms between the 2 nuclei division.

25. Changes in the Rate of Mitosis
Changes often occur in the growth rate of cells.
Faster Rate of Mitosis:
CANCER
_______________________
Slower Rate of Mitosis:
AGING
_______________________

26. Regulation of the Cell Cycle
External factors
Physical signal – cell to cell contact. Once a cell touches another cell it stops dividing.
When cells fail to respond to the external signal, the cells continue to divide uncontrollably and form clumps.
Tumor – is a clump of cancer cells.
Benign – tumor is harmless, the cells are clustered together tightly and can be removed.
Malignant – tumor is bad, the cells can break away and be carried to other parts of the body.
When a tumor has metastasized, it means the cancer cells have spread to other parts of the body.

27. Why are tumors Harmful?
Cancer cells do not perform the specialized functions needed by the body.
In the lung – cancer cells do not exchange oxygen and carbon dioxide.
In the brain – they do not transmit the messages needed to interpret information to the body
Can exert great pressure on surrounding organs.

28. Cancer 1. CHEMICALS Chemicals used on household items Drugs
Carcinogen – a substance known to produce or promote the development of cancer cells.
1. CHEMICALS
Chemicals used on household items
and/or pesticides, tobacco
Drugs
Nuclear Wastes
2. RADIATION
3. SOME VIRUSES
HPV
Sun
X-Rays

29. cancer cell
bloodstream
normal cell

30. Meiosis (cell reproduction)
Cuts chromosome number in half.
Creates haploid cells.
Creates sperm and egg
Spermatogenesis – the creation of sperm
Oogenesis – the creation of ova (egg)
Meiosis (cell reproduction)

31. Sperm or Eggs In males: These cells develop into
4 individual sperm that are genetically different from the parent cell.
In females:
These cells would have developed into 3 small polar bodies which will die and only 1 large egg.
(THIS IS DUE TO AN UNEVEN DIVISION OF CYTOPLASM DURING MEIOSIS)

32. Fertilization: Union of sperm and Egg Creates a zygote
Re-establishes the full number of chromosomes
2 chromosomes
2 chromosomes
4 chromosomes 32

33. Mitosis vs. Meiosis To make sperm and eggs with Occurs in sex cells
For growth and to replace old, worn out cells.
Occurs in body cells
Two cells from 1 cell
Identical cells to the parent cell.
Same number of chromosomes as the original (2N) - diploid
One division of the nucleus.
To make sperm and eggs with
Occurs in sex cells
Four cells from 1 cell
Genetically different from the parent cell.
Half the number of chromosomes (1N) - haploid
Two divisions of the nucleus. 33