1. DNA and Mitosis review/Meiosis
How do your cells divide?
This PowerPoint has many animated slide progressions. You may only want to print the following slides: 1-11, 14-15, 22-47

2. A few words before we start…..
Haploid: half of a full
set (only 1 set of DNA)
Diploid: full set (1 set from
each parent (2 sets)
Haploid – number of chromosomes in sex cells represented by n indicating one chromosome
Diploid - number of chromosomes in somatic cells represented by 2n indicating a set or double number of chromosomes

3. A Cell’s Life Interphase
Have students notice that the majority of a cell’s life is spent in interphase and during that time, the cell is performing all it’s cellular processes needed to survive. Indicate that M is Mitosis, the small amount of time the cell spends dividing.
Picture taken from

4. Why Do Cells Divide? Growth Damaged cells Sex cells
Answers are animated so you can ask students the question before you reveal the answers
Maintain workable surface area to volume - too big-can’t work!!
Replace damaged cells
Produce sex cells
Sex cells

5. Cell Reproduction
is either sexual or asexual

6. Asexual Reproduction (one parent)
Binary Fission-
Budding
Vegetative Propagation
Regeneration
Advantages?
Binary Fission - split in two (bacteria)
Budding- (Yeast)
Vegetative Propagation - (Plants)
Regeneration -
Disadvantages?

7. Asexual reproduction Advantages: Disadvantages: Doesn’t require a mate
Takes less time
Disadvantages:
All offspring are the same (genetically)

8. Sexual Reproduction 2 “parents” or 2 sets of DNA
Examples: humans, plants, dogs

9. Sexual reproduction Advantages Disadvantages? DIVERSITY!!!!!!!!!!
Offspring are genetically different from parents.
Disadvantages?
Need a mate
Takes longer

10. DNA Replication Before a cell can divide the DNA must replicate
(make a copy of itself)

11. DNA Replication Making a new strand of DNA is actually quite easy.
Replication occurs in 3 easy steps…

12. 1. DNA Unzips An enzyme (helicase) unzips the molecule
The enzymes breaks the hydrogen bonds that hold the nitrogen bases together.

13. DNA Replication DNA UnzipsG T C
This animation of DNA unzipping will proceed on it’s own

14. DNA Replication DNA UnzipsG
This animation of DNA unzipping will proceed on it’s own

15. DNA Replication DNA UnzipsG
This animation of DNA unzipping will proceed on it’s own

16. DNA Replication DNA UnzipsG
This animation of DNA unzipping will proceed on it’s own

17. DNA Replication DNA UnzipsG
This animation of DNA unzipping will proceed on it’s own

18. DNA Replication DNA UnzipsG
This animation of DNA unzipping will proceed on it’s own
Left Strand
of Original DNA
Right Strand
of Original DNA

19. 2. Base Pairing
Complementary bases match with each DNA strand in the open helix
DNA polymerase

20. DNA Replication Base Pairing
Left Strand
Original DNA
This animation of DNA pairing up will proceed on it’s own
Right Strand
Original DNA

21. DNA Replication Base Pairing
Left Strand
Original DNA
This animation of DNA pairing up will proceed on it’s own
Right Strand
Original DNA
New Right
DNA Strand

22. DNA Replication Base Pairing
Left Strand
Original DNA
This animation of DNA pairing up will proceed on it’s own
Right Strand
Original DNA
New Right
DNA Strand

23. DNA Replication Base Pairing
Left Strand
Original DNA
This animation of DNA pairing up will proceed on it’s own
Right Strand
Original DNA
New Right
DNA Strand

24. DNA Replication Base Pairing
Left Strand
Original DNA
This animation of DNA pairing up will proceed on it’s own
Right Strand
Original DNA
New Right
DNA Strand
New Left
DNA Strand

25. DNA Replication Base Pairing
Left Strand
Original DNA
This animation of DNA pairing up will proceed on it’s own
Right Strand
Original DNA
New Right
DNA Strand
New Left
DNA Strand

26. DNA Replication Base Pairing
Left Strand
Original DNA
Have students notice that there are two strands of DNA that are exactly alike
Right Strand
Original DNA
New Right
DNA Strand
New Left
DNA Strand

27. 3. DNA Zips Up
An enzyme (ligase) zips the new molecules back up.

28. DNA Replication
Voila!
Two identical
strands of DNA! T C A G

29. DNA Replication Review
Step 1
Step 2
Step 3
Step 1 – DNA unzips
Step 2 – Complementary bases match with each DNA strand in the open helix
Step 3 – DNA zips up

30. Remember - All this takes place in INTERPHASE

31. Now that DNA has replicated, we are ready to begin Mitosis (nucleus
of the cell divides)
Remind students Mitosis is an asexual cellular reproduction T C A G T C A G

32. Interphase: Parent Cell, chromosomes replicated
Prophase: Chromatin condenses into chromosomes, nuclear envelope disappears, centrioles move to opposite poles, spindle fibers form.
Metaphase: Chromosomes align on the equator
Have students look at the pictures and try to figure out what is happening to the DNA in each.
The slide is animated so you can ask the questions and reveal the answers when you are ready
Anaphase: Chromosomes separate and chromatids are pulled to opposite poles
Telophase: DNA uncoils, nuclear membrane reappears

33. Cytokinesis
Cleavage (indention in cell membrane) or cell plate formation occurs.
Cell divides.
Cytokinesis almost always follows mitosis. This is what creates two separate cells. Ask students what would happen if you have mitosis without cytokinesis (one cell with two nuclei).
Animal Cell
Plant Cell

34. Mitosis Animation
This animation is a review of mitosis. Have students review what is happening to the chromosomes.
Animation from

35. It’s all about the chromosomes!
There are 46 in human body cells
The number of chromosomes remain constant during Mitosis
Very important to emphasize that the number of chromosomes during mitosis remain constant.

36. Which Cells Go Through Mitosis?
Somatic (body) cells:
Cells which help the body in:
Growth
Repair
Explain the reason the chromosome number remains the same is because Mitosis is producing somatic cells (Skin, hair, muscle, etc.)
Work

37. Mitosis Review 1. Is the beginning parent cell diploid or haploid
(2n or n)?
2. Are the daughter cells diploid or haploid (2n or n)?
Questions are animated so you can ask each question and get an answer before going to the next question.

38. More Mitosis Review 3. How many daughter cells are produced?
4. Are the resulting daughter cells different from the parent cell?

39. More Mitosis Review
5. Are the resulting daughter cells different from each other?
6. How many chromosomes are in a human parent cell?
Questions are animated so you can ask each question and get an answer before going to the next question.
7. How many chromosomes are in a human daughter cell?

40. More Mitosis Review 8.What types of cells are produced by mitosis?
9. Why (when) does a cell go through mitosis?

41. Meiosis
Sexual Reproduction (two parents)

42. Why Meiosis? Meiosis - The production of gametes
Meiosis is the production of sex cells (gametes). During meiosis, the number of chromosomes in the daughter cells are reduced from the number of chromosomes in the parent cell (this is extremely important).

43. Interphase Cell growth
DNA replication  sister chromatids held together by centromere

44. Prophase I The chromosomes coil up and a spindle forms.
Homologous chromosomes line up with each other gene by gene along their length, to form a four-part structure called a tetrad.

45. Prophase I – crossing over
Crossing over occurs between homologous chromosomes  new genetic combinations that are different from the parent.

46. Metaphase I
The spindle fibers pull the tetrads into the middle, or equator of the cell.
There is no rule to who is on left or right side  independent assortment.

47. Anaphase I
Homologous chromosomes separate and move to opposite ends of the cell.

48. Telophase I
The spindle is broken down, the chromosomes uncoil slightly, and the cytoplasm divides to yield two new cells.
Each cell has half the DNA as the original cell because it has only one chromosome from each homologous pair.  Haploid

49. Remember mitosis?
Meiosis II looks just like mitosis except there is no DNA replication during interphase

50. Prophase II
A spindle forms in each of the two new cells and the spindle fibers attach to the chromosomes.

51. Metaphase II.
Sister chromatids, are pulled to the center of the cell and line up randomly at the equator.

52. Anaphase II
The sister chromatids separate and move to opposite poles.

53. Telophase II
Finally nuclei reform, the spindles breakdown, and the cytoplasm divides.
Four haploid cells have been formed from one diploid cell
All are genetically different from each other and from the parent cell.

55. How does Meiosis Occur? Animation of meiosis to use as a review
Meiosis Animation from

56. Why meiosis is important
Forms gametes for sexual reproduction
Crossing over and independent assortment  different genetic combinations.  diversity!!!

57. Meiosis Review
Is the beginning parent cell diploid or haploid (2n or n)?
2. Are the resulting daughter cells diploid or haploid (2n or n)?
Questions are animated so you can ask each question and get an answer before going to the next question.

58. More Meiosis Review 3. How many daughter cells are produced?
Are the resulting daughter cells different
from the
parent cell?

59. More Meiosis Review
5. Are the resulting daughter cells different from each other?
6. How many chromosomes are in a human parent cell?
Questions are animated so you can ask each question and get an answer before going to the next question.
7. How many chromosomes are in a human daughter cell?

60. More Meiosis Review
8. What types of cells are produced by meiosis?

61. Fertilization Mom Dad 23 46 New Individual 23
Formation of a new individual through the union of parent cells
The number of chromosomes are animated so you can ask students the answers before it comes up
New Individual 46

62. This is how new organisms are made!!

63. Mitosis and Development
Sexual reproduction
Haploid gametes
(n=23)
Sperm Cell
Meiosis
Meiosis
Egg Cell
Fertilization
Diploid zygote
(2n=46)
Mitosis and Development
Multicellular
diploid adults
(2n=46)

64. Let’s review
Mitosis & Meiosis

65. Visual review of the differences between mitosis and meiosis

66. Mitosis vs. Meiosis √ √ √ √ √ √ Event Mitosis Meiosis Produces 4 cells
Mitosis vs. Meiosis
Event
Mitosis
Meiosis
Produces 4 cells
Produces 2 cells
New cells identical
New cells different
New cells have the same number of chromosomes as parent
New cells have fewer chromosomes than parent √ √ √ √
The answers are animated so you can have students answer the question before you reveal the answer. √ √

67. Mitosis vs. Meiosis √ √ √ √ √ Event Mitosis Meiosis
Mitosis vs. Meiosis
Event
Mitosis
Meiosis
Beginning cells diploid (2n)
Beginning cells haploid (n)
Ending cells diploid (2n)
Ending cells haploid (n)
Produces egg and sperm
Produces body cells √ √
The answers are animated so you can have students answer the question before you reveal the answer. √ √ √