1. Why do cells need to divide?
Cell Size Limitations
Why do cells need to divide?
Surface area to volume ratio
Plasma membrane relative to cell volume
Transport of substances
More efficient in smaller cells
Cellular communications
If urgent signals sent to organelles are not received quick enough, cell could die

2. Cell Cycle INTERPHASE The process of a cell growing and dividing
5 Stages of the cell cycle:
G1 Phase= Cell GROWS and performs normal functions
S Phase= SYNTHESIS of DNA (DNA is replicated)
G2 Phase= Cell prepares for mitosis by making specialized proteins, and taking inventory of cell
ALSO KNOWN AS
INTERPHASE

3. Cell Cycle Continued….
4. Mitosis= Nuclear division (4 phases) 5. Cytokinesis= Cellular division into 2 identical daughter cells

4. MITOSIS Nuclear division in Eukaryotic cells
Equal separation of genetic info
Results in 2 identical “daughter cells”
New cells allow for growth & replacement of damaged cells
4 Stages

5. Prophase Chromatin condenses into visible chromosomes(fuzzy X’s)
Nuclear membrane disappears
Centrioles migrate to poles of cell
Spindle fibers form
Spindle fibers attach to centromeres
Spindle apparatus-centrioles & spindle fibers; organize chromosomes during division
*Longest phase of Mitosis

6. Metaphase Chromosomes align at equator (MIDDLE) of cell
Pulled to equator by spindle fibers attached to centromeres
Ensures both new cells receive correct chromosomes
* Shortest phase

7. Anaphase Chromatids pulled to opposite poles
Spindle apparatus shortens causing the separation

8. Telophase Chromosomes arrive at opposite poles
Chromosomes de- condense
2 nuclear membranes begin to form
Spindle apparatus disintegrates

9. Cytokinesis Pinching or constricting of the cytoplasm (animal cells)
Area of constriction called “furrow”
Forming a new cell plate or cell wall (plant cells)
Separates the 2 new identical daughter cells

10. Cancer Uncontrolled growth and division
Failure of regulation during cell cycle