1. Cell Reproduction Unit

2. Chromosome Structure
- chromosome = a long continuous thread of DNA that consists of numerous genes with regulatory information coiled around proteins in compact structures

3. Chromosome Structure
- DNA wraps around proteins (called histones) to become compact

4. Chromosome Formation

5. Chromosome Structure (cont)
Chromatid
Centromere

6. Cell Cycle
= the regular pattern of growth, DNA duplication, and cell division that occurs in cells

7. - results in two cells (daughter cells) identical to one another
Cell Cycle
- results in two cells (daughter cells) identical to one another
- made up of 5 Phases

8. 3) G2 Phase = cell prepares for cell division
Cell Cycle (cont)
1) G1 Phase = cell growth
2) S Phase = DNA is copied
3) G2 Phase = cell prepares for cell division
Together Phases 1-3 are called Interphase

9. 4) M Phase (Mitosis) - division of the nucleus
Cell Cycle (cont)
4) M Phase (Mitosis) division of the nucleus
5) C Phase (Cytokinesis) division of the cytoplasm

10. Sequence of the Cell Cycle G1 S G2 M C
Cell Cycle (cont)
Sequence of the Cell Cycle
G S G M C

11. Cell Cycle (cont)

12. Cell Cycle (cont)

13. = division of the nucleus and its contents
Mitosis
= division of the nucleus and its contents
- discovered by Walther Flemming in 1882

14. Phases of Mitosis

15. 1) Prophase - DNA coils to become chromosomes
- nuclear membrane disappears
- microtubules called spindle fibers grow from centrioles to center of cell

16. 1) Prophase (cont) Spindle Fibers: 2 Types
1) Kinetochore Fibers – attach to chromosomes (at centromere)
2) Polar Fibers – spread throughout cell

17. Prophase
Centrioles
Nucleus with Chromosomes
Spindle Fibers

18. Late Prophase
Kinetochore Fibers
Polar Fibers

19. 2) Metaphase
- chromosomes line up in center

20. Metaphase

21. 3) Anaphase
- chromosomes pull apart and move to opposite sides of cell

22. Anaphase

23. 4) Telophase
- chromosomes uncoil
- nuclear membrane reforms

24. Telophase
Chromosomes Uncoil
New Nuclear Membrane Forms

25. Phases of Mitosis

26. How do you remember the order of the phases of Mitosis?
Just remember this phrase……….

27. PMAT
PEE
MATT
P = Prophae
M = Metaphase
A = Anaphase
T = Telophase

28. Cytokinesis
- cell membrane forms a cleavage furrow and cytoplasm divides
- in plants, a cell plate forms between each cell

29. Cytokinesis
Cleavage Furrow

30. Cell Plate

31. Regulation of Cell Division
- controlled by external and internal factors
- External Factors
1) cell to cell contact
2) growth factors

32. Cell to Cell Contact

33. Regulation of Cell Division (cont)
Growth Factors – Examples
- Platelets

34. Regulation of Cell Division (cont)
Growth Factors – Examples
- Erythropoietin
(stimulates red
blood cell
production)

35. Regulation of Cell Division (cont)
- Internal Factors
- enzymes and proteins released by the cell

36. Regulation of Cell Division (cont)
- apoptosis = programmed cell death
Webbed Fingers

37. Apoptosis – Leaves in Fall

38. Incomplete Apoptosis

39. Cancer cells form tumors that may metastasize to other parts of the body
Normal Cell
Bloodstream
A healthy cell may become a cancer cell if certain genes are damaged

40. Cancer cells form tumors that may metastasize to other parts of the body
Cancer cells divide more often than do healthy cells and may form disorganized clumps called tumors

41. Cancer cells form tumors that may metastasize to other parts of the body
Sometimes cancer cells break away from the tumor. They can be carried in the bloodstream to other parts of the body where they form new tumors.

42. According to the American Cancer Society, skin cancer is the most common of all cancers.
This cancerous mole is an example of a skin cancer, which may metastasize quickly.

43. ABCD Rule (for moles, etc)
Mnemonic to help remember what to look for
A = Asymmetry (irregular shape)
B = Border is irregular shape
C= Color change (changing or many colors)
D = Dimension (1/4 in or less)
**other key signs to look for:
New growth, changes in growth, painful feeling

44. Look for the ABCD Rule in this mole?

45. Why is sex with someone else better than sex by yourself?

46. Asexual Reproduction
= reproduction of offspring from one parent
- offspring are genetically identical to the parent
…this is a BAD thing

47. Sexual Reproduction
= reproduction of offspring from two parents
- offspring are genetically different from the parents
…this is a GOOD thing

48. Nut Disease in Squirrels
Example
Nut Disease in Squirrels

49. Some eukaryotic cells divide by mitosis

50. Some organisms can reproduce by asexual or sexual reproduction (depends on conditions)

51. Meiosis

52. Meiosis
= cell reproduction that forms gametes (= sex cells = egg/sperm)

53. Meiosis (cont)
- # of chromosomes is halved
- produces haploid cells
(23 chromosomes)

54. Meiosis (cont) Two Stages: Meiosis I
Prophase I, Metaphase I, Anaphase I, Telophase I
Meiosis II
Prophase II, Metaphase II, Anaphase II, Telophase II

55. Meiosis (cont) Homologous chromosomes line up ( = tetrad)
Portions of chromatids are exchanged ( = crossing over)
- results in new mixture of genetic material ( = genetic recombination)

56. genetic recombination
Meiosis (cont)
tetrad
crossing over
genetic recombination

57. Meiosis (cont)
Chromosomes separate randomly ( = law of independent assortment)
- results in genetic variation

58. Meiosis (cont)

59. Spermatogenesis
= production of sperm cells
- makes 4 haploid cells called spermatids

60. Spermatogenesis

61. Oogenesis
= production of egg cells
- makes 1 haploid egg cell and 3 polar bodies
- polar bodies degenerate

62. Oogenesis

63. Examples: Mitosis vs. Meiosis

64. Examples: Mitosis vs. Meiosis
A human has 46 chromosomes
- after mitosis, each body cell has 46 chromosomes
- after meiosis, each sex cell (egg and sperm) has 23 chromosomes