1. Cell Growth and Cell Division
Cell growth is limited by the transportation of materials in and out of the cell.
If a cell grows too large, the amount of raw materials needed to get in and the wastes to get out is insufficient and the cell will die.
For an organism to get bigger, it does not need bigger cells, it just needs more cells.
In order for the total number of cells to increase and for an organism to grow, the cells must undergo cell division.

2. The Cell Cycle
Every cell undergoes a series of time periods during its ‘life’
Interphase is a period of growth & DNA replication- the cell prepares to divide
Mitosis or division is the splitting of a nucleus into two new ones
Cytokinesis is the splitting
of cytoplasm to form new cells.

3. Interphase The longest phase of the cell cycle is interphase.
The cell is performing life functions, but is not actually dividing.
Chromatin is the threadlike coils of protein and DNA that can be seen in the nucleus.
Chromatin is copied (replicated) and condenses into chromosomes at the end of interphase.

4. Interphase

6. Cell Division (Mitosis)
During cell division, one cell divides into two new cells.
Each new cell called a daughter cell, is identical to the other and to the parent cell.
Cell division occurs in a series of stages or phases.
Mitosis is the process by which the nucleus of a cell divides into two nuclei and the formation of two new daughter cells begins.

7. In Mitosis: Prophase
The first stage of cell division is called prophase when the process of mitosis begins.
Chromosomes are formed and the centrioles move to the opposite ends of the cell.
Mesh-like spindles begins to develop between the centrioles forming a “bridge” between the opposite ends.
The nuclear membrane and nucleolus disappear.

9. In Mitosis: Metaphase The second stage of mitosis is metaphase.
The chromosomes begin to attach to the middle of the spindle that runs from end to end of the cell.
The chromosomes are attached to the spindle by the centromere.

11. In Mitosis: Anaphase The third stage of mitosis is anaphase.
The chromosomes begin by separating from each other and moving toward opposite ends of the cell.

13. In Mitosis: Telophase
Stage 4 is telophase; chromosomes begin to uncoil back into chromatin.
The nuclear membrane reforms around the chromatin at each end of the cell.
In each of the newly formed nucleus, the nucleolus reappears.
Nuclear division is now complete.

15. Cytokinesis
Before re-entering interphase, the cell has to go thru cytokinesis.
The cytoplasm is divided as the cell membrane begins to move inward and pinch it off; or in a plant cell a new cell wall is formed.
Each part now contains a nucleus with identical chromosomes.
The cell membrane fully forms and two new daughter cells are produced.