1. Cell Division
Cell Cycle and Mitosis

2. Objectives What are the main events of the cell cycle?
What are the four phases of mitosis?

3. Eukaryotes Plants & animals
Cell Reproduction
Prokaryotes Bacteria
Eukaryotes Plants & animals

4. Prokaryotes Lack a nucleus Have a single chromosome
Reproduce by binary fission
Include bacteria

5. Steps in Binary Fission
Used by bacteria
Cells increase their cell mass slightly
DNA & cell components are replicated
Each cell divides into 2 daughter cells

6. Eukaryotes Contain a nucleus & membrane bound organelles
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Eukaryotes
Contain a nucleus & membrane bound organelles
Asexually reproduce cells by mitosis

7. Events of the Cell Cycle
G1: first growth phase (growth, making of new proteins and organelles)
S: DNA is doubled (DNA replicates)
G2: second growth phase (organelles and molecules required for division are produced)
M phase: Cell Division (mitosis)

8. Cell Cycle Review
What happens during
each phase?

9. Structure of a Chromosome
Sister chromatids
Wound up DNA
Also called Sister Chromatids or Homologous Chromosomes when occurring in pairs

10. Cell Types (Eukaryotic)
Body Cells (Somatic Cells): All the cells of your body – except the sex cells.
Sex Cells – sperm, eggs – (Gametes): The cells used for reproduction.

11. Body Cells (Somatic Cells)
Chromosomes are in matched pairs called homologous (same) chromosomes—same size, shape, and carry the same genes for the same traits. Humans have 46 chromosomes in EACH CELL! (They are found in 23 pairs) Chromosomes are copied in order to get ready for the process of MITOSIS.

12. Mitosis (Cell Division of Somatic (Body) Cells )
Prophase
Interphase
Cytokinesis
Metaphase
Telophase
Anaphase

13. Interphase
Interphase is the period of growth that occurs between cell divisions.
Loose DNA (chromatin)
Nucleus present

14. Prophase (Chromosomes Present)
Chromosomes condense and become visible.
The centrioles separate and take up positions on opposite sides of the nucleus. Form spindle fibers.
The nuclear envelope breaks down.

15. Metaphase (Chromosomes in Middle)
Chromosomes line up in the center of the cell.
Spindle fibers (microtubles) connect the centromere of each chromosome to the poles of the spindle.

16. Anaphase (Chromosomes move Apart)
The sister chromatids separate into individual chromosomes and move toward opposite sides of the cell.
Individual
chromosomes

17. Telophase (Chromosomes Totally Apart)
Chromosomes gather at opposite ends of the cell and lose their distinct shape.
A new nuclear envelope forms around each cluster of chromosomes.

18. Cytokinesis (Complete)
* Not part of Mitosis *
During cytokinesis, the cytoplasm pinches in half.
Each daughter cell has an identical set of duplicate chromosomes