Biology Mitosis

1. Mitosis
What is it?
Why is it
Important?
What do I
need to
know?

2. Why more cells?
 Populations of
single-cell critters
 Multicellularity?
 We all start out as
a single cell…?
 The zygote…
 & become/remain
multicellular

3. Binary Fission…Monera

4. Binary Fission..DNA
duplicates…why?

5. DNA separates & new cell
wall divides cell in two

6. 2 ‘new’ cells…identical?

7. Binary Fission

8. quiz
 What happens to the size of bacteria
after binary fission?
 What has to happen before fission
occurs?
 What benefit(s) do bacteria derive
from binary fission (as opposed to
sexual reproduction)?

9. Eukaryotic cells??
 The nucleus?
 Nuclear membrane
 Chromosomes…not
chromosome…?
 All that ‘stuff’ in
the cytoplasm?

10. Eukaryotic cell cycle
 Cell is ‘born’
 Duplicates DNA??
 Grows to…size?
 Prepares to divide
 Divides=mitosis

13. Control of mitosis:CYCLIN

14. The nuclelus must first
divide before the cell can
 Why?
 How?
 How much time of
the cell cycle/life
can be spent in
mitosis?

15. Chromosomes duplicate

20. Kinetochore (centromere)

30. Mitosis produces identical
offspring (2N---2N)

31. Why some cells stop mitosis…
differentiation
 Muscle cells…
 Nerve cells…
 Critical functions
might be disrupted
 Adaptations to this
condition

32. Importance???
 Growth
 Replacement
 Cancer
 Regeneration of…

33. Cancer?
 Unregulated
mitosis
 Benign
 Malignant/
metastasis
 How does it begin?

34. Normal cycle controls
 Internal signals
 External signals:
growth factors
fibronectin,etc
carcinogens
 Apoptosis
 Immune functions
 And…

35. Cell immortilization!!
 Hayflick limit??
 Hela cells
 Contact inhibition
 Increased
telomerase activity
 = immortalization!

36. Immortalization???
 If you replaced…
 Why not??…look at
your shoestrings?
 Telomerase &
telomeres & …?
 Recently…
 Implications???

37. Mitosis quiz Use two words to describe the
importance of mitosis
 Draw and label the cell cycle…include
G1, S, G2, M and cytokinesis…what
happens at each stage?
 Why might telomerase be important?
 What disease is associated with
mitosis?
 Are all organisms limited to 50 mitotic
divisions?

38. Name stage of mitosis

39. Name stage of mitosis

40. Name stage of mitosis

41. Name stage of mitosis

42. Name stage of mitosis

43. Name stage of mitosis

44. Name stage of mitosis

45. Name stage of mitosis

46. These are bacteria
 Watch the clip
 What kind of
reproduction is
shown here?
 What advantage
does this confer on
the organism?