IV. External & Internal Controls of Cell Division
Density Dependent Inhibition Crowding inhibits cell division why Anchorage dependence why Conclusion – 2 reasons cell division is halted
Introduction Different cells divide at different times and rates: Human skin cells Liver cells Muscle & nerve cells
Evidence from Cell Culture Studies & Growth Factors Figure Method – allowed identification of growth factor PDGF
Restriction Point (G o ) What and when Result Examples Most cells Liver Nerve
VII. Cyclical Changes in Regulatory Proteins Function as a Mitotic Clock Figure 12.17
Introduction Controls exist Reason
Control Mechanism by interactions of protein kinases & cyclins Terms: Protein kinases Definition Action Cyclins Definition Function MPF (maturation Promoting Factor) Definition Composition
Five Steps in Control Process
VIII. Cancer Cells & Cell Division Don’t respond to controls – 3 ways Characteristics Not affected by Can stop Are immortal – HeLa Cells
Consequences of loss of normal controls Tumor formation Types Benign Malignant Can metastasize Definition Reason Metastasis