1. The Cell Cycle
Ch. 10

2. Cell Cycle Regulation
Cell growth and division are carefully controlled.
Not all cells will go through the cell cycle at the same rate.
Examples of cells
rapidly dividing:
Examples of cells NOT dividing often:
Skin cells
RBC
Muscle cells
Nerve cells
Bone
marrow
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_Cancer_(Non-Meloma)/The_Basics/Epidermis-dermis.jpg
Digestive
tract cells
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3. Cell Cycle Regulation continued . . .
Cells that do not need to grow and divide can
enter G0 (resting) until they are needed.

4. Regulation Cells have both internal and external regulators.
Are all of the chromosomes attached
to spindle fibers and properly
aligned on the metaphase plate?
Internal regulators—are called cyclins and are a family of proteins that make sure the cell is ready at certain checkpoints . . .
If not, stops the cycle (see diagram)
Is the cell
big enough?
Has all of the DNA duplicated completely or properly?
Is the cell big enough?

5. Regulation continued . . . External regulators—
are called growth factors.
If cells are touching other cells = no growth
If space with no neighboring cells = grow/divide
Density-dependent inhibition

6. Cancer What happens if cells LOSE the
ability to CONTROL the cell cycle?
Cancer

7. Cancer Cancer = uncontrolled cell growth
. . . cancer cells do NOT respond to regulator signals
. . . results in masses of cells called tumors
. . . cancer = a disease of the cell cycle