1. Mitosis & the Cell Cycle
Fall 2009

2. Cell Growth & Development
Are cells of organisms the same size? Do your cells get bigger as you grow, or do you just produce more cells?
When talking about Cell Size…… Smaller is Better!
The larger a cell becomes, the more demands the cell places on its DNA, and the harder it is to supply with nutrients.

3. Cell Division
Before a cell becomes to large, a growing cell will divide.
Cell division is the process by which a Single cell divides into 2 Daughter cells.
Cell Division = the series of events that cells go through as they grow and divide.

4. Chromosomes
Chromosomes= are composed of DNA-Which carries the cell’s coded genetic information.
Humans have 46 chromosomes(23 pairs).
The chromosomes consist of two identical sister chromatids.

5. Two Major Types of Cell Division
Mitosis- Somatic cells (Body Cells)
Diploid 2N
Meiosis- Sex cells/ Gametes
Haploid 1N

6. Mitosis
Mitosis is the process by which the genetic information is replicated and distributed to daughter cells.
2 diploid(2N) daughter cells are produced from 1 diploid (2N) parent cell.
The Daughter cells are genetically identical to the parent cell.
There are 4 major stages to mitosis, PMAT. Mitosis does NOT include interphase.

7. Interphase
Interphase= The cell spends most of its life here; not part of the actual reproduction. NOT PART OF MITOSIS.
Cell grows and replicates its DNA and centrioles.
Nuclear membrane is visible
Nucleus, Nucleolus, and chromatin can be seen.

8. Interphase

9. Prophase Prophase: first phase of Mitosis Centrioles separate
Nuclear membrane breaks down
Chromosomes become visible
Centrioles separate
Spindle forms

10. Metaphase Metaphase: Second part of Mitosis
Chromosomes attach to spindle
Chromosomes line up across the center of the cell

11. Anaphase Anaphase: Third step in Mitosis
The sister chromatids separate into two groups near the poles of the spindles. The chromatids are now called chromosomes.

12. Telophase Telophase: Fourth stage of Mitosis
Chromosomes gather at opposite ends of the cell
The nuclear membrane begins to form and enclose the chromosomes
Cell membrane begins to move inwards

13. Cytokinesis Not Mitosis Works with telophase
Cytokinesis: Final stage in cellular division
Not Mitosis
Works with telophase
The cytoplasm divides completely in half.
2 daughter cells with identical genetic information are produced.

14. Cancer: Loss of Cell Control
All cancer is due to genetic mutation
Most mutations occur during an individual’s lifetime and are not inherited (although some people have inherited a genetic predisposition for a higher likelihood that mutations will occur)
The signals that turn on the cell cycle remain on and the signals that block excessive division remain off. Division does not stop!
Cancer cells, if given a continual supply of nutrients, are immortal.
A mass of abnormal cells called a tumor forms
A malignant tumor – cancer cells remain at the original site
Metastasis – cancer cells have spread

15. Treatment
High-energy radiation that damages DNA in cancer cells
Cancer cells have lost the ability to repair damage!
2. Chemotheraphy – toxins that interfere with cell division are administered