1. Recall that DNA is instructions for making protein.

2. Just as a cookbook is divided into recipes…

3. …DNA is divided into segments called “genes.”
Cyclin

4. Cyclin
Protein that controls the rate of the cell cycle. P R C C

5. In other words, cyclin controls how often a cell divides.
Cyclin A
Cyclin B

6. Skin cells divide every 24 hours.
Cyclin A

7. Liver cells: divide every year.
Cyclin B

8. Nerve cells NEVER divide…X
Cyclin C

9. …which is why brain and spinal cord injuries are permanent.

10. Again, cells know how often to divide because cyclin protiens “tell” them what to do.
Skin Cells
Liver Cells
Nerve Cells
Every 24 hours
Every year
Never

11. So what would happen to a cell without cyclin?

12. Without cyclin, the cell would move through the cell cycle too fast and would divide uncontrollably.

13. A mass of cells, called a tumor, forms.

14. This condition is known as cancer.

15. Cancer
Unregulated cell division caused by cyclin proteins not being made, or being made incorrectly. D C I

16. How the @(%#*% does cyclin change?

17. ribosome DNA Amino acids
Like all proteins, cyclin is made by the cell’s ribosomes following DNA instructions. P C R D
ribosome
DNA
Cyclin
Amino acids

18. ribosome DNA Amino acids
If the DNA changes, the cyclin could be made incorrectly, leading to cancer. D C C I C
ribosome
DNA
Cyclin
Amino acids

19. And how the @(%#*% does DNA change???

20. DNA is a molecule. Something with enough energy could break its bonds.
Radiation

21. 1. Radiation (solar, nuclear, etc.)

22. 2. Chemicals C

23. Cancer caused by radiation

24. Skin cancer (melanoma) is caused by solar radiation.

25. Melanoma happens when solar radiation breaks bonds in the cyclin gene
Melanoma happens when solar radiation breaks bonds in the cyclin gene. Other proteins are not affected. X
Cyclin

26. Melanoma often affects moles, because the darker-colored cells absorb more solar radiation.

27. On its own, melanoma is not very dangerous, since the tumor forms on the outside of the body. Such tumors can be easily removed.
Radiation

28. However, if left untreated, a skin tumor can metastasize.
Radiation

29. Metastasis
NEW PAGE
The spread of cancer throughout the body; happens when a piece of a tumor breaks off and enters the bloodstream. S B T B

30. Nuclear radiation, such as that released by a nuclear explosion, has more energy that UV radiation. So it affects all cells of the body – not just the ones on the outside.
Radiation

31. Also, the entire DNA molecule is affected by nuclear radiation – not just one gene. So, all proteins are affected. X X X
Cyclin X

32. https://nuclearsecrecy.com/nukemap/
Exposure to nuclear radiation usually causes death before cancer develops.
Radiation

33. Radiation sickness in Hiroshima, 1945:

34. Nuclear radiation affects you inside and out, so unborn babies are also affected:

35. Cancer caused by chemicals
Radiation

36. Lung cancer is caused by exposure to chemicals (such as tobacco smoke).
Radiation

37. Other chemicals, such as solvents and cleaners, can also cause lung cancer if they are inhaled.
Radiation

38. Lung cancer happens when the cyclin gene reacts with the inhaled chemicals.X
Cyclin

39. Tumor in dissected lung:
Radiation

40. Lung tumors in an x-ray (metastasized):
Radiation

41. Even if you are not exposed to radiation or chemicals, you can still get cancer.

42. Cancer can also be caused by random errors during DNA replication.

43. DNA replication:
Replication Enzyme