6-2 Mitosis and Cell Division

- Binary Fission is a process in which bactteria divide to form identical copies.

- Bacteria is a prokaryotic cells and lack a nucleus and organelles.

- Bacteria's DNA does not form Chromosomes

- During Binary Fission the bacteria cell'ss DNA replicates (makes a copy of itself) and then the cell splits into two equal halves.

- Cell division in Eukaryotic cells is callled the Cell Cycle.

G1 --> S --> G2 --> M --> C

- Stages of the Cell Cycle

1. ) Growth Phase 1 - The cell simply grows and carries out it's normal routine.
   
   
2. ) Sequencing Phase - DNA is copied and chromosomes form two chromatids attached together by a centromere
   
   
3. ) Growth Phase 2 - The cell continues to grow and organelles replicate.

(The first 3 phases of the Cell Cycle are known as Interphase)

) Mitosis - The nucleus divides into two identical nuclei

) Cytokinesis - Cytoplasm divides and then the cell divides into two equal halves each containing a nucleus and organelles.

- Stages of Mitosis

1. ) Prophase - Enzymes break down the nuclear envelope, chromosomes begin to condense and centrioles form spindle fibers.
   
   
2. ) Metaphase - Chromosomes line up in the center of the cell and protein disks called Kinetochore form microtubules to attach to the spindle fibers.
   
   
3. ) Anaphase - The spindle fibers pull the chromatids apart towards opposite ends of the cell.
   
   
4. ) Telephase - A new nuclear envelope forms around each set of chromosomes on opposite ends of the cell as the chromosomes uncoil and two new nuclei have formed.

- Information in the nucleus of a cell conttrols when and how often a cell will divide. When cells begin to replicate out of control they are said to be cancerous.