1. Recall that M phase is the part of the cell cycle when the cell divides.
GROWTH
DNA LOOSENS G1
CYTOPLASM DIVIDES
INTERPHASE
M PHASE
NUCLEUS DIVIDES S
DNA REPLICATION G2
CHROMOSOMES FORM
CHECK FOR ERRORS

2. M phase is divided into two main parts.
GROWTH
DNA LOOSENS G1
CYTOPLASM DIVIDES
(CYTOKINESIS)
INTERPHASE
M PHASE
NUCLEUS DIVIDES S
(MITOSIS)
DNA REPLICATION G2
CHROMOSOMES FORM
CHECK FOR ERRORS

3. Mitosis First part of M phase; division of the nucleus. Nucleus

4. Cytokinesis
SKIP ½ PAGE
Nucleus
Nucleus
Nucleus
Nucleus
Last part of M phase; division of the cytoplasm and organelles. L C O

5. WHAT PROBLEMS DOES A CELL FACE DURING MITOSIS?
Nucleus
Nucleus
Nucleus

6. Chromosomes are trapped in the nucleus
PROBLEM
SOLUTION
Chromosomes are trapped in the nucleus
Get rid of the nucleus!

7. Chromosomes didn’t divide equally
PROBLEM
SOLUTION
Chromosomes didn’t divide equally
Line up the chromosomes in the middle!

8. Chromosomes are stuck together Pull the chrosomes apart!
PROBLEM
SOLUTION
Chromosomes are stuck together
Pull the chrosomes apart!

9. Chromosomes need to be enclosed in a nucleus
PROBLEM
SOLUTION
Chromosomes need to be enclosed in a nucleus

10. Chromosomes need to be enclosed in a nucleus
PROBLEM
SOLUTION
Chromosomes need to be enclosed in a nucleus
Form two new nuclei!

11. Mitosis occurs in 4 careful steps…
GROWTH
DNA LOOSENS C G1
CYTOPLASM DIVIDES
(Cytokinesis)
INTERPHASE
M PHASE
NUCLEUS DIVIDES S
DNA REPLICATION
(Mitosis) G2
CHROMOSOMES FORM
CHECK FOR ERRORS

12. …to ensure that the daughter cells get an equal number of chromosomes.

13. INTERPHASE M PHASE G1 S PROPHASE G2 GROWTH DNA LOOSENS
CYTOPLASM DIVIDES
(Cytokinesis)
INTERPHASE
M PHASE
NUCLEUS DIVIDES S
DNA REPLICATION
(Mitosis)
PROPHASE G2
CHROMOSOMES FORM
CHECK FOR ERRORS

14. Prophase
NEW PAGE
First step of mitosis; fully-formed chromosomes appear, and the nucleus starts to disappear. M C N

15. Organelles called centrioles move to opposite ends of the cell.

16. The centrioles will pull the chromosomes apart.

17. Additionally, spindle fibers appear during prophase
Additionally, spindle fibers appear during prophase. They grow out from the centrioles and attach to the chromosomes. S F P C C
Chromosomes
Spindle fiber
Centrioles

18. Prophase “Before” Centrioles Fully-formed chromosomes
Nucleus disappears
Spindle fibers

19. INTERPHASE M PHASE G1 METAPHASE S PROPHASE G2 GROWTH DNA LOOSENS
CYTOPLASM DIVIDES
(Cytokinesis)
INTERPHASE
M PHASE
NUCLEUS DIVIDES
METAPHASE S
DNA REPLICATION
(Mitosis)
PROPHASE G2
CHROMOSOMES FORM
CHECK FOR ERRORS

20. Metaphase
“Middle”
Step 2 of mitosis; chromosomes line up along the middle of the cell. M L U M

21. Motor proteins pushing chromosomes into position during metaphase (discovered in 2012):

22. INTERPHASE M PHASE G1 ANAPHASE METAPHASE S PROPHASE G2 GROWTH
DNA LOOSENS G1
CYTOPLASM DIVIDES
(Cytokinesis)
INTERPHASE
M PHASE
ANAPHASE
NUCLEUS DIVIDES
METAPHASE S
DNA REPLICATION
(Mitosis)
PROPHASE G2
CHROMOSOMES FORM
CHECK FOR ERRORS

23. Anaphase
“Not”
Step 3 of mitosis; chromosomes are pulled apart by the spindle fibers. M C A S F

24. The spindle fibers pull the chromosomes apart by contracting (getting shorter).

25. INTERPHASE M PHASE G1 TELOPHASE ANAPHASE METAPHASE S PROPHASE G2
GROWTH
DNA LOOSENS G1
CYTOPLASM DIVIDES
(Cytokinesis)
INTERPHASE
M PHASE
TELOPHASE
ANAPHASE
NUCLEUS DIVIDES
METAPHASE S
DNA REPLICATION
(Mitosis)
PROPHASE G2
CHROMOSOMES FORM
CHECK FOR ERRORS

26. Telophase
“Away”
Final step of mitosis; chromosomes move away from each other, and a nucleus re-forms around each set of chromosomes. M A N C

27. What happens if mitosis does not occur correctly?

28. It is EXTREMELY important that chromosomes split equally….

29. …especially during the division of sex cells.

30. If chromosomes don’t split equally during the formation of sex cells…
Wrong number of chromosomes

31. …the resulting baby could have the wrong number of chromosomes.
Mother
Father

32. Which stage of mitosis is this?
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis

33. Cytokinesis occurs immediately after mitosis.

34. Cytokinesis is different in animal and plant cells.
Rigid
Cell wall

35. Cytokinesis in Animal Cells vs. Plant Cells

36. In animal cells, protein fibers in the middle of the cell contract, pinching the cell in two.

37. In plant cells, the cell wall is too rigid to pinch
In plant cells, the cell wall is too rigid to pinch. Instead, a cell plate forms. P C W R P

38. After cytokinesis, the DNA loosens so that the cell cycle can start over.

39. Mitosis + Cytokinesis

40. Go Sally Go Make Children
Interphase
M Phase Go
Sally Go
Make
Children G1 S G2
Mitosis
Cytokinesis P M A T

41. Identifying Cells in M Phase

42. Identifying Cells in the Cell Cycle Fully-formed chromosomes
No chromosomes G1
Small (just divided)
Fully-grown
Interphase S
End of G2
DNA starting to condense
Fully-formed chromosomes
Prophase
& no nucleus
Metaphase
M phase
Anaphase
Mitosis
Telophase

43. Mitosis cells: fully-formed chromosomes, no nucleus

44. Prophase?

45. Identifying Cells in the Cell Cycle
No chromosomes G1
Small (just divided)
Fully-grown
Interphase S
End of G2
DNA starting to condense
Before chromosomes have lined up
Fully-formed chromosomes
Prophase
& no nucleus
Metaphase
M phase
Anaphase
Mitosis
Telophase

46. Metaphase?

47. Identifying Cells in the Cell Cycle
No chromosomes G1
Small (just divided)
Fully-grown
Interphase S
End of G2
DNA starting to condense
Before chromosomes have lined up
Fully-formed chromosomes
Prophase
Chromosomes lined up in the middle
& no nucleus
Metaphase
M phase
Anaphase
Mitosis
Telophase

48. Anaphase?

49. Identifying Cells in the Cell Cycle
No chromosomes G1
Small (just divided)
Fully-grown
Interphase S
End of G2
DNA starting to condense
Before chromosomes have lined up
Fully-formed chromosomes
Prophase
Chromosomes lined up in the middle
& no nucleus
Metaphase
Chromosomes are not attached (still close)
M phase
Anaphase
Mitosis
Telophase

50. Telophase?

51. Identifying Cells in the Cell Cycle
No chromosomes G1
Small (just divided)
Fully-grown
Interphase S
End of G2
DNA starting to condense
Before chromosomes have lined up
Fully-formed chromosomes
Prophase
Chromosomes lined up in the middle
& no nucleus
Metaphase
Chromosomes are not attached (still close)
M phase
Anaphase
Chromosomes move away; divided nucleus
Mitosis
Telophase

52. What about this cell?

53. Identifying Cells in the Cell Cycle
No chromosomes G1
Small (just divided)
Fully-grown
Interphase S
End of G2
DNA starting to condense
Before chromosomes have lined up
Fully-formed chromosomes
Prophase
Chromosomes are lined up in the middle
& no nucleus
Metaphase
Chromosomes are not attached (still close)
M phase
Anaphase
Chromosomes move away from each other
Mitosis
Telophase
DNA starting to loosen;
Cytokinesis

54. Additionally, during cytokinesis, a line starts to form between the two daughter cells.
Contracting protein fibers
Cell plate

55. Identifying Cells in the Cell Cycle
No chromosomes G1
Small (just divided)
Fully-grown
Interphase S
End of G2
DNA starting to condense
Before chromosomes have lined up
Fully-formed chromosomes
Prophase
Chromosomes are lined up in the middle
& no nucleus
Metaphase
Chromosomes are not attached (still close)
M phase
Anaphase
Chromosomes move away from each other
Mitosis
Telophase
DNA starting to loosen;
Cytokinesis
Line starts to form