1. The Cell Cycle Roles of Cell Division The Mitotic Cell Cycle
Regulation of the Cell Cycle

2. Role of Cell Division Reproduction, growth, and repair
Daughter cells are clones

3. The Mitotic Cycle Alternates interphase and mitotic phase (mitosis)
Well-ordered
Some cells rarely divide
Interphase: G1, S, G2
M phase: Mitosis and cytokinesis

4. Interphase 90% of the cell cycle
G1 phase-cell functioning as a normal cell
S phase-synthesis phase, occurs when DNA is replicated
G2 phase-cell disassembles cytoskeleton, begins formation of spindle proteins
Go some cells never progress past this phase

5. Mitotic Cell Division Karyokinesis (mitosis)
consists of prophase, metaphase, anaphase and telophase
Cytokinesis (cytoplasmic division)
differs in animal and plant cells

6. The Mitotic Spindle Microtubules Assembly begins in centrosome
2 types: kinetochore and nonkinetochore microtubules
Kinetochore microtubules separate and organize chromosomes
Nonkinetochore microtubules elongate cell

7. Cytokinesis Animals-forms a cleavage furrow
Contractile ring of actin microfilaments
Plants-forms a cell plate
Golgi apparatus produces vesicles

8. Regulation of the Cell Cycle
Molecular control system drives the cycle
Consists of a set of checkpoints
Checkpoints integrate internal and external information
Synchronized by rhythmic changes in protein kinases
Cyclins activate kinases

9. Cues for the Cell Cycle Internal:
kinetochores cue M-phase checkpoint (identify the state of spindle attachment
External
1) chemical-absence of essential nutrients, presence of growth factors
2) physical-density-dependent inhibition, anchorage dependence

10. Cancer Cells do not respond normal to control mechanisms
No density dependent inhibition
Make their own growth factors
Abnormal cell cycle
Unusual number of chromosomes possible
Aberrant metabolism
Lost attachment to neighboring cells and to ECM

11. Videos and Websites

12. Videos and Websites (2)