1. Don’t Panic
Bonus #1 due today

2. DNA Replication, Mitosis, and Cancer

3. Genes are the parts of DNA that contain information.
CB 5.25
Protein

4. For life to exist, the information (genes) must be passed on.
{Meiosis:
producing gametes}
For life to exist, the information (genes) must be passed on.
{Mitosis:
producing more cells}

5. Mitosis

6. The Cell Cycle
[DNA Replication]
CB 12.4

7. Complementary base pairs suggest how DNA replication may occur

8. DNA replication: each strand serves as a template for making a complementary copy
Origin of Replication

9. DNA replication: each strand serves as a template for making a complementary copy
helicase
O.R.
helicase

10. DNA replication: each strand serves as a template for making a complementary copy
helicase
helicase
The two strands of DNA are unwound.

11. DNA replication: each strand serves as a template for making a complementary copy
helicase
helicase
The DNA is copied.

12. DNA replication: each strand serves as a template for making a complementary copy
helicase
helicase
More unwinding, more copying

13. DNA replication: each strand serves as a template for making a complementary copy
helicase
helicase
The DNA has now been copied. There are now two double-stranded DNAs

14. Most DNA has multiple origins of replication
CB 16.10

15. each strand serves as a template for producing a complementary copy
DNA replication:
each strand serves as a template for producing a complementary copy
CB 5.27

16. Sometimes errors are made.

17. Error
Luckily, errors can be repaired.

18. DNA Repair mismatch removed by enzymes DNA replaced repair complete
damage
or replication
error
CB 16.17

19. Not all errors get repaired.
These are mutations.

20. Errors are made during DNA replication
3,000,000,000 (3 billion) base pairs/human cell
with
1 error/1 billion base pairs not repaired
= (average)
~6 errors each time DNA is replicated

21. Mutations

22. Cancer: Cell Division Gone Wrong

23. Cell division is regulated by both positive and negative signals
Cell division is regulated by both positive and negative signals. Positive signals start the process of cell division. Negative signals inhibit cell division.

24. CB 12.13

25. Normal Mammalian Cells Have Contact Inhibition
CB 12.16

26. Cancer Cells
Do Not Have
Contact Inhibition
CB 12.16

27. Cancer: is the loss of control over cell division.
Tumors are normal cells that are
dividing inappropriately.
They stop performing their “normal” function, and are dividing repeatedly.

28. Tumors in a Liver
normal
tumors

29. Normal Cells
Cancer Cells

30. A cell becomes cancerous when there are incorrect positive AND negative signals.

31. GO!
STOP!
cancer
CB 19.13

32. Multiple mutations are required for a single cell to become cancerous.
CB 19.14

33. Benign versus Malignant cancer
CB 12.17

34. How do these incorrect signals arise?
Multiple mutations are required for a single cell to become cancerous.
CB 19.14

35. Mutations
CB 17.22

36. Don’t Panic
Bonus #1 due today