1. Meiosis and Mitosis

2. What is a chromosome? Linear strand of packaged DNA
In the nucleus of eukaryotic cells

3. Haploid Cells (1N) Sex cells or gametes are haploid!
Reproductive Cells (gametes that contain 23 single chromosomes)
Male Gamete:
Sperm: produced in the testes
Female Gamete:
Egg: produced in the ovaries
Ova-plural
Ovum- singular
Human Haploid # = 23

4. SPERM: 22 autosomal chromosomes and an X or a Y sex chromosome
Haploid (1N) Sperm Cell
23 single chromosomes
SPERM: 22 autosomal chromosomes and an X or a Y sex chromosome
Human sex cell karyotype. A karyotype is the complete set of chromosomes of an organism. However, this karyotype comes from an oocyte (immature egg cell) and so has only the haploid (half, 23) number of chromosomes. If the egg is fertilised the chromosomes from the sperm cell will join with these chromosomes to form a whole genome of 46 chromosomes arranged in 23 pairs.
or an X
Sex chromosomes
Autosomal chromosomes

5. EGG: 22 autosomal chromosomes and an X sex chromosome
Haploid (1N) Egg Cell
23 single chromosomes
EGG: 22 autosomal chromosomes and an X sex chromosome
Sex chromosomes
Autosomal chromosomes

6. Fertilization occurs and produces a…..

7. Diploid Cell with Homologous Chromosomes
Homologous Pair
One diploid cell with
46 homologous chromosomes (a pair of chromosomes- one from each parent)
23 total pairs = 46 chromosomes

8. Fertilization union of sperm and egg (gametes)
Produces a diploid zygote with 46 homologous chromosomes
results in sharing and exchanging of genetic information
This allows for species variation in sexually producing organisms.

9. Fertilization Fertilization X or X 1n XY
46 homologous chromosomes in this diploid zygote
Zygote = fertilized egg
23 single chromosomes 1n XY 1n
X or X
23 single chromosomes

10. Diploid Cells (2N) Somatic (Body) Cells are diploid!
Non-reproductive cells such as muscle, skin, blood
contain 46 total chromosomes (23 pairs)
have two homologous copies of each chromosome-one from the mother and one from the father
Mom
Dad
Human Diploid # = 46

11. Karyotype- organized profile of an organism’s chromosomes within one cell
Homologous Pair
22 pairs of autosomal chromosomes (44 total)
This is a karyotype of a diploid body cell from a male.
1 pair of sex chromosomes
(2 total)

12. Human Karyotype

13. HUMAN SEX CHROMSOMES

14. The sex of a person depends on whether the sperm that fertilizes the egg contains an X or a Y chromosome.
46 total
46 total

15. The process of mitosis begins after a sperm fertilizes an egg.

16. Fertilization Results In a Diploid (2n) Zygote
Egg 1n
Haploid
nucleus
Sperm 1n
Haploid
nucleus

17. Fertilization Results In a Diploid Zygote
Egg 1n
Haploid
nucleus
Sperm 1n
Haploid
nucleus

18. Fertilization Results In a Diploid Zygote
Egg 1n
Haploid
nucleus
Haploid
nucleus
Sperm 1n

19. Fertilization Results In a Diploid Zygote
Egg 1n
Haploid
nucleus
Haploid
nucleus
Sperm 1n

20. The zygote undergoes mitosis (cell division).

21. From Zygote to Embryo 2n 2n 2n

22. From Zygote to Embryo 2n 2n

23. From Zygote to Embryo 2n 2n 2n 2n

24. From Zygote to Embryo 2n 2n 2n 2n

25. From Zygote to Embryo All cells are diploid (2n)!

26. Cell Differentiation
During week two of embryonic development, embryonic cells have begun the process of differentiation. The identical cells formed by the early divisions of the zygote are beginning to take on the different characteristic of muscle, blood, nerve, bone, and other kinds of cells.
Different genes are turned on in different cells.

27. From Embryo to Fetus
Fetal Stage- Week 9

28. To a Multicellular Human

29. diploid zygote with 46 chromosomes
We are here right now…
Now the zygote will undergo mitosis to grow into a multicellular organism XY XX
diploid zygote with 46 chromosomes
Multicellular
Organism
= 46 chromosomes
union of gametes
Egg
23 haploid chromosomes
Sperm
23 haploid chromosomes

30. Videos Fertilization Animation with Narration (Start at 11s)
Fertilization Animation (Start at 3:23)
Cell Differentiation

31. MITOSIS (A.K.A. Cell Division)
Asexual reproduction of eukaryotic somatic (body) cells

32. Three reasons why body cells reproduce by asexual reproduction: 1
Three reasons why body cells reproduce by asexual reproduction: Growth Repair Replacement

33. Chromosomes and Chromatids
centromeres
A chromosome may be a single chromatid or it may be two sister chromatids joined by a centromere.
1 Chromatid
1 Chromosome
2 Sister Chromatids
1 Chromosome

34. DNA replication produces sister chromatids during interphase
DNA replication produces sister chromatids during interphase. This doubles the amount of genetic information in the cell and helps to ensure the two daughter cells will each contain the same number of chromosomes as the parent cell.
Interphase
Prophase

36. 3 Stages to the Cell Cycle92 46
DNA Replicates
Start: 1 cell with 46 chromosomes 92
End: 2 genetically identical cells each with 46 chromosomes 46 46 92 46 46

37. IPMATC REMEMBER! I Procrastinate More At The Caribbean
Stage 1: Interphase
Stage 2: Mitosis
Prophase
Metaphase
Anaphase
Telophase
Stage 3: Cytokinesis
IPMATC Mi
tosis
A mnemonic to help remember the stages of mitosis.
I Procrastinate More At The Caribbean 37

40. The Cell Cycle (Mitosis) in an Animal Cell

41. Stage1- Interphase Cell is diploid (2N)- homologous chromosomes
The nucleus and nucleolus are very distinct
Chromosomes appear as threadlike coils (chromatin) at the start
DNA replicates - chromosome number doubles and sister chromatids begin to form
Nucleolus
Cell membrane
Nucleus
-2 Pairs of
Homologous
Chromosomes
-4 chromatids/ 4 chromosomes
Cytoplasm

42. Sister Chromatids
two exact copies of a chromosome attached together by a centromere
created during DNA replication during interphase

44. Interphase
Plant Cell
Animal Cell

45. Stage 2
Mitosis

46. Prophase - 1st step in mitosis
Centrioles appear and begin to move to opposite ends of the cell (Only animal cells have centrioles! )
Spindle fibers form between the poles
Chromosomes condense (become visible)
Nuclear membrane starts to break down
2 Pairs of Homologous Chromosomes
8 Sister Chromatids
4 Chromosomes
Centrioles
Spindle Fibers

47. Prophase
Plant Cell
Animal Cell

48. Metaphase - 2nd step in mitosis
Centrioles have reached the poles of the cell
Centromeres of sister chromatids attach to the spindle fibers and line up in the middle.
Nuclear membrane disappears
8 Sister Chromatids
4 Chromosomes
Centromere
Centrioles
Spindle fibers

49. Metaphase
Plant Cell
Animal Cell

50. Anaphase - 3rd step in mitosis
Sister chromatids separate and move to poles
Ensures each daughter cell has the same number of chromosomes as the parent cell
8 Chromosomes
8 Chromatids
Centrioles
Spindle fibers

51. Anaphase
Plant Cell
Animal Cell

52. Telophase - 4th step in mitosis
Animal Cells: cell membrane begins to pinch inwards to form a cleavage furrow
Plant Cells: cell plate begins to form into a cell wall
Both Cells:
Nuclear membrane forms
Two new nuclei visible
Diploid chromosomes appear as chromatin
Nucleus
Nucleus
Chromatin

53. Telophase
Plant Cell
Animal Cell

54. Cleavage Furrow in an Animal Cell

55. Stage 3. Cytokinesis Division of cytoplasm
Two diploid daughter cells created – each with a nucleus and an identical number of chromosomes 2N 2N 2N 2N

56. Cytokinesis

57. Mitosis produces two identical diploid (2n) daughter cells
1-Interphase
2-Mitosis
3-Cytokinesis
Two cells that are genetically identical to each other and the parent cell are formed.

59. Animal Mitosis - Review
Interphase                                                             
Prophase                                                             
Metaphase                                                             
Anaphase                                                             
Telophase                                                             
Cytokinesis                                                             

60. Plant Mitosis - Review Interphase Prophase Metaphase Anaphase
Telophase                                                             
                                                           
Cytokinesis  

61. Cell Cycle Time Frame
2 daughter cells
-It takes about 24 hours for one cell to complete the cell cycle and 80 minutes for most eukaryotic cells to undergo mitosis.
1 parent cell

62. What if mitosis runs rampant?
CANCER- uncontrolled cell division
Cancer cells do not respond to the signals that regulate cell growth.
Cancer Video
Cancer Video 2
Cancer is a disease of uncontrolled cell division. It starts with a single cell that loses its control mechanisms due to a genetic mutation. That cell starts dividing without limit, and eventually kills the host.
Normal cells are controlled by several factors.
Normal cells stay in the G1 stage of the cell cycle until they are given a specific signal to enter the S phase, in which the DNA replicates and the cell prepares for division. Cancer cells enter the S phase without waiting for a signal.
Normal cells are mortal. This means that they can divide about 50 times and then they lose the ability to divide, and eventually die. This “clock” gets re-set during the formation of the gametes. Cancer cells escape this process of mortality: they are immortal and can divide endlessly.
Normal cells that suffer significant chromosome damage destroy themselves due to the action of a gene called “p53”. Cancer cells either lose the p53 gene or ignore its message and fail to kill themselves.

64. Postmitotic (nonmitotic) Cells
Do not do mitosis after reaching maturity.
Include:
Skeletal Muscles
Heart (Cardiac Muscles)
Smooth Muscle (Stomach)
Neurons
Brain

65. Mitosis Review Videos http://www.cellsalive.com/mitosis.htm
Mitosis Rap
Mitosis Dance 1
Mitosis Dance 2
Mitosis Animation
Textbook animation
Twilight Mitosis
Twilight Mitosis Short Version
Mitosis Cartoon- Amoeba Sisters
Mitosis: Splitting up is Complicated

66. Why must gametes have half the genetic material of body cells?
Recall that the gametes each have 23 chromosomes. During fertilization the zygote inherits 23 chromosomes from the mother’s egg and 23 chromosomes from the father’s sperm.
If the gametes did not have half the number of chromosomes, the chromosome number would double with each fertilization, and after a few generations, the number of chromosomes in each cell would become impossibly large!

67. diploid zygote with 46 chromosomes
Now the zygote will undergo mitosis to grow into a multicellular organism XY XX
diploid zygote with 46 chromosomes
Multicellular
Organism
= 46 chromosomes
union of gametes
Egg
23 haploid chromosomes
Sperm
23 haploid chromosomes

68. So how do sex cells become haploid?

69. Meiosis A.K.A Reduction Division
-Production of sex cells with half the number of chromosomes as a body cell.
-Cell division of 1 diploid (2n) cell resulting in 4 haploid (1n) cells
-Gametes are produced in the ovaries (female) and the testes (male)

70. 1 diploid (2n)
Parent cell
4 haploid (1n)
daughter cells

72. Synapsis and Crossing Over
During Prophase I of meiosis, homologous chromosomes pair up (synapsis) and exchange genetic information. This is known as crossing over. Crossing over allows gametes to receive a unique set of genetic information and produces variation of a species. Crossing Over Video

73. During meiosis, the chromosome pairs separate and are distributed to two different cells. The resulting sex cells have only half as many chromosomes as the other cells in the organism.

76. Mitosis and Meiosis Relationship

77. Meiosis Review Videos Meiosis Animation
Meiosis Square Dance Review Video
Tutorial Review! Click Here
Why do ferns have more chromosomes than you?
Meiosis Crash Course
Meiosis 3D animation
Meiosis Amoeba Sisters

78. Mitosis vs. Meiosis

80. Meiosis vs. Mitosis Review Videos
ThinkWell Review
The continuation of Life...a good overall review of the mitosis and meiosis relationship
Meiosis and Mitosis Compare and Contrast Review Tutorial
PBS How Cells Divide: Mitosis vs Meiosis Interactive
Where do your genes come from?
Crash Course in Meiosis

81. Helpful Website

82. So how do twins form?

83. Videos…Twins How do twins form?
National Geographic- In the Womb (2:55)