1. Chapter 9
Cell Reproduction

2. Cell Division
Cell division is the process by which cells reproduce themselves

3. Cell Division
Cell division in eukaryotes includes the division of the nucleus (mitosis) and division of the cytoplasm (cytokinesis)

4. Concept 9.1 - All cells come from cells
The division of cells into more cells enables living things to repair damage, to grow and to produce offspring

5. Cell Repair & Growth
Enables your body to produce new cells to replace dead cells

6. Reproduction Asexual Sexual
Single cell duplicates its genetic material and splits into 2 genetically IDENTICAL cells
Sexual
Genetic material from each of 2 parents combine, producing offspring that differ genetically from either parent

7. Asexual Reproduction
Asexual reproduction is the formation of offspring from one parent
Offspring produced by asexual reproduction are genetically identical to the parent

8. Asexual Reproduction

9. Binary fission is the process of cell division in prokaryotes

10. Sexual Reproduction
Sexual reproduction is the formation of offspring through the union of a sperm and an egg
Offspring produced by sexual reproduction are genetically different from the parents

11. Sexual Reproduction

12. Concept 9.2 – The cell cycle multiples cells
At this moment, millions of cells in your body are dividing, each forming 2 new cells.

13. Chromosomes
Almost all of the genes of a eukaryotic cell are located in the nucleus.
Most of the time, this genetic material exists in long fibers too thin to be seen under a light microscope.
As a cell prepares to divide – these fibers condense and become visible as chromosomes.

14. Chromosomes

15. Chromosomes are tightly coiled DNA molecules and associated proteins

16. In eukaryotes, histone proteins help maintain the compact structure of chromosomes
DNA
Histone

17. In dividing cells, chromosomes are composed of 2 identical chromatids constricted together at a centromere

18. Chromosomes are categorized as either sex chromosomes or autosomes

19. Chromosomes
Homologous chromosomes consist of one autosomal chromosome from each parent

20. Cell Cycle
The cell cycle goes from the “birth” of a cell until it reproduces itself.

21. Cell Cycle Interphase 90% of the cell cycle is spent here
Stage where the cell performs its functions
Increasing proteins, releasing enzymes, etc
G1, S, and G2 stages
G1 – Gap 1 = Cell grows
S – DNA Synthesis = Genetic material copied
G2 – Gap 2 = Cell prepares to divide

22. Cell Cycle Mitotic Phase Contains 2 processes Mitosis Cytokinesis
Nucleus and duplicated chromosomes divide and are evenly distributed, forming 2 “daughter” nuclei
Cytokinesis
Cytoplasm is divided into 2

23. Cell Cycle
The cell cycle is the repeating of events that make up the life of a cell
The cell cycle consists of cell division and interphase

24. Concept 9.3 Cells divide during the mitotic phase
Cell Division
Concept 9.3
Cells divide during the mitotic phase

25. Interphase
Interphase consists of a phase of growth (G1), a phase of DNA replication (S), and a phase of preparation for cell division (G2)

26. Interphase G1 = Cell is in a resting phase, performing cell functions
                                
                                
                                
                                
Interphase
(technically not part of mitosis, but it is included in the cell cycle)
Cell is in a resting phase, performing cell functions
DNA replicates (copies)
Organelles double in number, to prepare for division
Interphase
(technically not part of mitosis, but it is included in the cell cycle)
Cell is in a resting phase, performing cell functions
DNA replicates (copies)
Organelles double in number, to prepare for division
Interphase
G1 = Cell is in a resting phase, performing cell functions
S = DNA replicates (copies)
G2 = Organelles double in number, to prepare for division

27. Mitotic Phase
Mitosis is divided into prophase, metaphase, anaphase, and telophase
PMAT
Mitosis results in two offspring cells that are genetically identical to the original cell

28. Prophase Spindle forms Centrioles move to opposite poles
                                
Prophase
Spindle forms
Centrioles move to opposite poles
Chromosomes become visible

29. Metaphase
Chromosomes line up along the equator

30. Anaphase Centromeres divide
Chromatids separate and move to opposite poles

31. Telophase Nuclear membrane forms around each group of chromosomes
                           
Telophase
Nuclear membrane forms around each group of chromosomes
Chromosomes unwind
Cytokinesis begins

32. Cytokinesis
The process by which the cytoplasm divides and one cell becomes two individual cells
Animals - cell pinches inward
Plants - a new cell wall forms between the two new cells

33. Mitosis Summary

34. Concept 9.4 – Cancer cells grow and divide out of control.
Timing during normal cell division is critical to normal growth and development.
When the “control system” malfunctions, cells may reproduce at the wrong time or in the wrong place.

36. Tumors & Cancer Benign tumors Malignant tumors Metastasis
Abnormal mass of essentially normal cells
Depending on their location they sometimes cause health problems
Often removed via surgery
Malignant tumors
Masses of cells that result from reproducing cancer cells
Cancer disrupts the timing of cell division – this disruption leads to uncontrolled cell division
Metastasis
Spread of cancer beyond its original site

37. Metastasis

38. Cancer Treatment
When possible, malignant tumors are removed with surgery
To treat cancer on the cellular level – radiation and chemotherapy is often used
Radiation exposes the cells to high energy radiation, which disrupts cells division
Chemotherapy involves treating patients with cytotoxic chemicals which prevent cell division
Different types of chemotherapy drugs affect cell division in different ways (preventing the spindle fibers from forming, “freezing” the spindle, etc)

39. Cancer Treatment
Radiation & Chemotherapy often causes undesirable side effects in normal body cells that rapidly divide
Radiation can affect ovaries & testes – and can cause sterility
Chemotherapy often damages intestinal cells or hair follicles (fast growing cells), causing nausea or hair loss

40. Concept 9.5 – Meiosis functions in sexual reproduction.
Only dogs produce more dogs, only trees produce more trees, and only people produce more people.
BUT: “Like begets similar to, but not exactly like.”

41. Diploid v. Haploid Cells
Almost all human cells are diploid
2n = 2 sets of homologous chromosomes
Human cells = 46 chromosomes
Only exception – sex cells are haploid
n = 1 set of homologous chromosomes
Human sex cells = 23 chromosomes

42. Diploid (2n) is the number of chromosomes in cells that have homologous pairs of autosomes and 2 sex chromosomes

43. Sex Sells
Haploid cells (n) have half the number of chromosomes that are present in diploid cells

45. Meiosis

46. Meiosis
Meiosis produces haploid daughter cells from specialized cells in diploid organisms.
Despite the similarity in their names, meiosis is different from mitosis in two major ways.
Meiosis produces four new offspring cells, each with one set of chromosomes—thus half the number of chromosomes as the parent cell.
Meiosis involves the exchange of genetic material between homologous chromosomes.

47. Meiosis
Goes through two divisions
Meiosis 1
Meiosis 2

48. Each pair of homologous chromosomes is called a tetrad
Homologous chromosomes (each with sister chromatids)
A tetrad
                                     
                            

49. Crossing-over during meiosis results in genetic recombination

50. During meiosis, a cell divides twice

51. Meiosis During the second cellular division, the DNA replicates again
This is how we result in half the number of regular chromosomes but four copies of the haploid cell
And now for some anatomy…

52. THE MALE

53. THE MALE ANATOMY

54. Spermatogenesis is the process by which sperm cells are produced

55. Sperm

56. THE FEMALE

57. THE FEMALE ANATOMY

58. Oogenesis is the process that produces egg cells (ova)

59. Human Egg

60. Egg

61. Huzzaa!