1. Chapter
Student

2. 8.7 Anchorage, cell density, and chemical growth factors affect cell division
The cells within an organism’s body divide and develop at different rates.
Cell division is controlled by
the presence of essential nutrients,
growth factors, proteins that stimulate division,
VEGF: vascular endothelial growth factor
density-dependent inhibition, in which crowded cells stop dividing, and
anchorage dependence, the need for cells to be in contact with a solid surface to divide.
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3. Anchorage Single layer of cells Removal of cells Restoration of single
Figure 8.7B
Anchorage
Single layer
of cells
Removal
of cells
Figure 8.7B An experiment demonstrating density-dependent inhibition, using animal cells grown in culture
Restoration
of single
layer by cell
division 3

4. 8.8 Growth factors signal the cell cycle control system
The cell cycle control system is a cycling set of molecules in the cell that
triggers and
coordinates key events in the cell cycle.
Checkpoints in the cell cycle can
stop an event or
signal an event to proceed.
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5. 8.8 Growth factors signal the cell cycle control system
There are three major checkpoints in the cell cycle.
G1 checkpoint
allows entry into the S phase
causes the cell to leave the cycle, entering a nondividing G0 phase.
G2 checkpoint, and
DNA replicated? Damaged?
M checkpoint.
Chromatids attached to spindles?
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6. G1 checkpoint G0 G1 S Control system M G2 M checkpoint G2 checkpoint
Figure 8.8A
G1 checkpoint G0 G1 S
Control
system M
Figure 8.8A A schematic model for the cell cycle control system G2
M checkpoint
G2 checkpoint 6

7. G1 checkpoint Receptor protein S G1 Control system M G2
Figure 8.8B
EXTRACELLULAR FLUID
Plasma membrane
Growth
factor
Relay proteins G1
checkpoint
Receptor
protein
Signal
transduction
pathway S G1
Control
system
Figure 8.8B How a growth factor signals the cell cycle control system M G2
CYTOPLASM 7

8. 8.9 Cancer: Out of control cell division
Transformation
Cancer cells escape controls on the cell cycle.
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9. 8.9 Cancer: Out of control cell division
Transformation
Cancer cells escape controls on the cell cycle.
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10. 8.9 Cancer: Out of control cell division
Cancer cells
divide rapidly, often in the absence of growth factors,
spread to other tissues through the circulatory system, and
grow without being inhibited by other cells.
Form tumors
Benign
Malignant, metastasis

11. Lymph vessels Blood vessel Tumor Tumor in another part of the body
Figure 8.9
Lymph
vessels
Blood
vessel
Tumor
Tumor in
another
part of
the body
Glandular
tissue
Figure 8.9 Growth and metastasis of a malignant (cancerous) tumor of the breast
Growth
Invasion
Metastasis 11

12. 8.9 Cancer: Out of control cell division
Cancers are named according to the organ or tissue in which they originate.
Carcinomas arise in external or internal body coverings.
Ex. Skin lining of intestine
Sarcomas arise in supportive and connective tissue.
Ex. Bone and muscle
Leukemias and lymphomas arise from blood-forming tissues.
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13. 8.9 Cancer: Out of control cell division
Cancer cells are immortal.
Cancer treatments
Surgery
Radiation
Chemotherapy is used for metastatic tumors.
Taxol (yew) freezes mitotic spindle
Vinblastin (periwinkle) mitotic spindle does not form
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