1. Discuss with group Look at notes from yesterday
Review cell cycle
Discuss with group
Look at notes from yesterday

2. Control of the Cell Cycle
Why is this important?

3. Not all of our cells behave in the same way
Not all of our cells behave in the same way. Most of our cells have very specialized functions that allow them to carry out their tasks. This is good, as long as everything works the way that it should all of our cells behave in the same way. Most of our cells have very specialized functions that allow them to carry out their tasks. This is good, as long as everything works the way that it should

4. Purpose Cells divide for different reasons Repair
Example = cut in your skin or a broken bone
Growth
Reproduction
Allow the baby to become strong and healthy

5. Speed of Growth Some cells grow and divide constantly
Example = skin, stomach, mouth
Some cells never divide
Example = Brain and nerve

6. Controls on the Cycle
Proteins called cyclins regulate the timing of cell cycle processes
Cyclins ‘tell’ the ell when to start and stop dividing
Allows normal cell cycle to be precisely controlled

7. OH NO!!! SOMETHING WENT WRONG
Consequences of uncontrolled cell growth are very severe

8. CANCER A ‘disease of the cell cycle’ Occurs because of a DNA mutation
Normal checkpoints regulating mitosis are ignored or overridden by the cancer cell
Causes abnormal cell growth
Tumors
Benign = non-spreading
Malignant = spreading
Usually grows uncontrollably
Cancerous cells divide repeatedly out of control even though they are not needed; they crowd out other normal cells and function abnormally. They can also change functioning of major organs
CANCER

10. Causes Errors during replication Aging Carcinogens (toxins) Examples =
Mutagens
Genetics

11. Cell Differentiation
Generic , less specialized cell, becomes a more specialized cell type
Occurs during development as we change from a zygote (fertilized egg cell) to a complex system of cells and tissues
Stem Cells develop into these specialized cells

12. How do cells differentiate?
Remember – all cells contain DNA
not all of the DNA is expressed in a cell
This is called GENE EXPRESSION
Specific pieces of our DNA are ‘turned on’ depending on the function of a cell

13. Regeneration Often serves as a defensive mechanism to escape predators
Animals lose a limb and can then regrow the lost appendage
Cells that mimic stem cells are found at the site where the arm, tail, or other body part may be lost
These cells then differentiate to form the correct piece of the animal
As the cells are replicating during MITOSIS they are reading certain pieces of the DNA
This GENE EXPRESSION is crucial to healthy and correct regrowth!

14. Axolotl