1. The Cell Cycle by: Ernsting at C:\Documents and Settings\Administrator\Local Settings\Temporary Internet Files\Content.IE5\1TIPHCP8\cc03a[1].ppt

2. Cell division functions in reproduction, growth, and repair

3. Important Terms (part one)
genome: all of a cell’s DNA
chromosome: individual DNA molecule
chromatin: chromosomal DNA and its
protein scaffold
sister chromatids: the two identical
copies of a duplicated
chromosome
centromere: the point of attachment for two sister chromatids
somatic cells: (most cells) have two copies of each chromosome (diploid)
gametes: (reproductive cells; sperm and eggs) have one copy of each
chromosome (haploid)

4. More Important Terms cell cycle: the process of cell division
mitosis (M phase) nuclear division
interphase: the main part of the cell
cycle
G1 phase - cell prepares for
DNA synthesis, usually
grows in size
S phase - DNA is duplicated
G2 phase - cell checks fidelity of DNA replication, prepares for
nuclear division
mitosis subphases - prophase, prometaphase, metaphase, anaphase,
telophase
cytokinesis

5. Mitosis (1)

6. Mitosis (2)

7. The Mitotic Spindle
The mitotic spindle is composed of microtubules, and directs the alignment of chromosomes on the metaphase plate.
During anaphase, the microtubules attached to each centromere guide the movement of chromosomes toward spindle poles.

8. Polar Depolymerization of Microtubules

9. Cytoplasmic Division
Microfilaments contract to divide the cytoplasm. Plant cells are less flexible, because of the cell wall, and deposit cell wall material between the two daughter cells.

10. Mitosis (differential staining)

11. Mitosis in Growing Tissue

12. Binary Fission in Bacteria

13. Evolution of Mitosis

14. Cell Cycle Control
The cell’s place in the cell cycle is signaled by the presence or absence of cell cycle kinases.
A growth signal leads to passage through the G0 restriction point into G1.
(See Fig 11.11)
The cell then executes a programmed series of steps that culminate in mitosis and cytokinesis.

15. is an example of kinase control of the cell cycle
is an example of kinase control of the cell cycle. It is like a license that allows the cell to begin M phase of the cell cycle.
MPF
MPF is a two-subunit enzyme. One subunit is Cdk (present during the whole cell cycle). The other subunit is a cyclin protein that builds up as M phase approaches.
When the cyclin concentration is high enough, cyclin binds to Cdk, forming the MPF enzyme. MPF activity signals the start of mitosis.

16. Cancer
Normal cells are transformed to tumor cells when cell division is not controlled.
Cancer cells are growth-factor independent.
Cancer cells have escaped density-dependent inhibition.
Most cancerous cells are destroyed by the immune system, but some cells progress from benign to malignant, and possibly to metastatic.

17. Cell Culture and Growth Factors

18. Density-dependent Inhibition
Density-dependent inhibition is a property of normal cells.
Cancer cells lack this inhibition.

19. Metastatic Cancer
Metastatic cancer cells spread throughout the body.