1. 1 Cellular Reproduction

2. 2 Types of Cell Reproduction Asexual reproduction involves a single cell dividing to make 2 new, identical daughter cells Asexual reproduction involves a single cell dividing to make 2 new, identical daughter cells 3 Reasons why cells undergo asexual Reproduction: 3 Reasons why cells undergo asexual Reproduction: 1.Growth 2.Repair 3.Replacement Examples: somatic cells (body), cancer cells Examples: somatic cells (body), cancer cells

3. 3 Five Phases of the Cell Cycle G 1 - primary growth phase G 1 - primary growth phase S – synthesis; DNA replicated S – synthesis; DNA replicated G 2 - secondary growth phase G 2 - secondary growth phase **collectively these 3 stages are called interphase M - mitosis M - mitosis C - cytokinesis C - cytokinesis

4. 4 The Cell Cycle Daughter Cells DNA Copied Cells Mature Cells prepare for Division Cell Divides into Identical cells http://www.cellsalive.com/mitosis.htm

5. Interphase 5 Occurs before Mitosis begins Chromosomes are copied (# doubles)Chromosomes are copied (# doubles) Chromosomes appear as threadlike coils (chromatin) at the start, but each chromosome and its copy (sister chromosome) change to sister chromatids at end of this phaseChromosomes appear as threadlike coils (chromatin) at the start, but each chromosome and its copy (sister chromosome) change to sister chromatids at end of this phase Remember: Remember: G 1 - primary growth phase G 1 - primary growth phase S – synthesis; DNA replicated S – synthesis; DNA replicated G 2 - secondary growth phase G 2 - secondary growth phase **collectively these 3 stages are called interphase Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm Animal Cell Plant Cell

6. 6 Mitosis Division of the nucleus Division of the nucleus Also called karyokinesis Also called karyokinesis Only occurs in eukaryotes (plants and animal cells) Only occurs in eukaryotes (plants and animal cells) Has four stages Has four stages Doesn’t occur in some cells such as brain cells Doesn’t occur in some cells such as brain cells

7. 7 Four Mitotic Stages Prophase Prophase Metaphase Metaphase Anaphase Anaphase Telophase Telophase

8. 8 Early Prophase Chromatin in nucleus condenses to form visible chromosomes Chromatin in nucleus condenses to form visible chromosomes Mitotic spindle forms from fibers in cytoskeleton or centrioles (animal) Mitotic spindle forms from fibers in cytoskeleton or centrioles (animal) Chromosomes Nucleolus Cytoplasm Nuclear Membrane

9. 9 Late Prophase Nuclear membrane & nucleolus are broken down Nuclear membrane & nucleolus are broken down Chromosomes continue condensing & are clearly visible Chromosomes continue condensing & are clearly visible Spindle fibers called kinetochores attach to the centromere of each chromosome Spindle fibers called kinetochores attach to the centromere of each chromosome Spindle finishes forming between the poles of the cell Spindle finishes forming between the poles of the cell

10. 10 Late Prophase Nucleus & Nucleolus have disintegrated Chromosomes

11. 11 Review of Prophase What the cell looks like What’s happening

12. 12 Metaphase Chromosomes, attached to the kinetochore fibers, move to the center of the cell Chromosomes, attached to the kinetochore fibers, move to the center of the cell Chromosomes are now lined up at the equator Chromosomes are now lined up at the equator Metaphase= “Middle” Metaphase= “Middle” Pole of the Cell Equator of Cell

13. 13 Metaphase Chromosomes lined at the Equator The poles of a cell Spindle Fibers

14. 14 Metaphase The pole of the cell Chromosomes at Equator Animal Cell Plant Cell

15. 15 Review of Metaphase What the cell looks like What’s occurring

16. 16 Anaphase Occurs rapidly Occurs rapidly Sister chromatids are pulled apart to opposite poles of the cell by spindle fibers Sister chromatids are pulled apart to opposite poles of the cell by spindle fibers Sister Chromatids being separated

17. 17 Anaphase Review What the cell looks like What’s occurring

18. 18 Telophase Sister chromatids at opposite poles Sister chromatids at opposite poles Spindle disassembles Spindle disassembles Two new nuclei form Two new nuclei form Nuclear envelope forms around each set of sister chromatids Nuclear envelope forms around each set of sister chromatids Nucleolus reappears Nucleolus reappears CYTOKINESIS occurs CYTOKINESIS occurs Chromosomes reappear as chromatin Chromosomes reappear as chromatin

19. 19 Comparison of Anaphase & Telophase

20. Telophase 20 Animal Cell Plant Cell Nuclei reforming Polar microtubules continue elongation

21. 21 Cytokinesis Means division of the cytoplasm Means division of the cytoplasm Occurs after mitosis Occurs after mitosis Division of cell into two, identical halves called daughter cells Division of cell into two, identical halves called daughter cells In plant cells, cell plate forms at the equator to divide cell In plant cells, cell plate forms at the equator to divide cell In animal cells, cleavage furrow forms to split cell In animal cells, cleavage furrow forms to split cell

22. 22 Cytokinesis Cleavage furrow in animal cell Cell plate in plant cell

23. 23 Daughter Cells of Mitosis Have the same number of chromosomes as each other and as the parent cell from which they were formed Have the same number of chromosomes as each other and as the parent cell from which they were formed Identical to each other, but smaller than parent cell Identical to each other, but smaller than parent cell Must grow in size to become mature cells (G 1 of Interphase) Must grow in size to become mature cells (G 1 of Interphase)

24. 24 Review Eukaryotic Cell Division Used for growth and repair Used for growth and repair Produce two new cells identical to the original cell Produce two new cells identical to the original cell Cells are diploid (2n) Cells are diploid (2n) Chromosomes during Metaphase of mitosis ProphaseMetaphase Anaphase Telophase Cytokinesis

25. 25 Mitotic Stages

26. 26 The Cell Cycle Animation You should be able to name each stage!!

27. 27 Review of Mitosis

28. 28 Interphase Prophase Metaphase Anaphase Telophase Name the Mitotic Stages: Name this?

29. 29 Mitosis in Onion Root Tips Do you see any stages of mitosis?

30. 30 Draw & Learn these Stages

31. 31 Draw & Learn these Stages

32. 32 Test Yourself over Mitosis

33. 33 Mitosis Quiz

34. 34 Mitosis Quiz

35. 35 Name the Stages of Mitosis: Interphase Early prophase Mid-Prophase Late Prophase Metaphase Late Anaphase Early Anaphase Early Telophase, Begin cytokinesis Late telophase, Advanced cytokinesis

36. 36 Identify the Stages Early, Middle, & Late Prophase Late Prophase MetaphaseAnaphase Late Anaphase Telophase Telophase & Cytokinesis ? ? ?? ? ??

37. 37 Locate the Four Mitotic Stages in Plants Metaphase Prophase Anaphase Telophase

38. 38 Uncontrolled Mitosis If mitosis is not controlled, unlimited cell division occurs causing cancerous tumors If mitosis is not controlled, unlimited cell division occurs causing cancerous tumors Oncogenes are special proteins increase the chance that a normal cell develops into a tumor cell Oncogenes are special proteins that increase the chance that a normal cell develops into a tumor cell Cancer cells

39. 39 Meiosis Formation of Gametes (Eggs & Sperm)

40. 40 Facts About Meiosis Preceded by interphase which includes chromosome replication Preceded by interphase which includes chromosome replication Two meiotic divisions --- Meiosis I and Meiosis II Two meiotic divisions --- Meiosis I and Meiosis II Called Reduction- division Called Reduction- division Original cell is diploid (2n) Original cell is diploid (2n) Four daughter cells produced that are monoploid (1n) Four daughter cells produced that are monoploid (1n)

41. 41 Facts About Meiosis Daughter cells contain half the number of chromosomes as the original cell Daughter cells contain half the number of chromosomes as the original cell Produces gametes (eggs & sperm) Produces gametes (eggs & sperm) Occurs in the testes in males (Spermatogenesis) Occurs in the testes in males (Spermatogenesis) Occurs in the ovaries in females (Oogenesis) Occurs in the ovaries in females (Oogenesis)

42. 42 Start with 46 double stranded chromosomes (2n) After 1 division - 23 double stranded chromosomes (n) After 1 division - 23 double stranded chromosomes (n) After 2nd division - 23 single stranded chromosomes (n) After 2nd division - 23 single stranded chromosomes (n) Occurs in our germ cells that produce gametes More Meiosis Facts

43. 43 Why Do we Need Meiosis? It is the fundamental basis of sexual reproduction It is the fundamental basis of sexual reproduction Two haploid (1n) gametes are brought together through fertilization to form a diploid (2n) zygote Two haploid (1n) gametes are brought together through fertilization to form a diploid (2n) zygote

44. 44 Fertilization – “Putting it all together” 1n =3 2n = 6

45. 45 Replication of Chromosomes Replication is the process of duplicating a chromosome Replication is the process of duplicating a chromosome Occurs prior to division Occurs prior to division Replicated copies are called sister chromatids Replicated copies are called sister chromatids Held together at centromere Held together at centromere Occurs in Interphase

46. 46 A Replicated Chromosome Homologs Homologs (same genes, different alleles) (same genes, different alleles) Sister Chromatids (same genes, same alleles) Gene X Homologs separate in meiosis I and therefore different alleles separate.

47. 47 Meiosis Forms Haploid Gametes Meiosis must reduce the chromosome number by half Meiosis must reduce the chromosome number by half Fertilization then restores the 2n number Fertilization then restores the 2n number from momfrom dadchild meiosis reduces genetic content too much! The right number!

48. 48 Meiosis: Two Part Cell Division Homologsseparate Sisterchromatidsseparate Diploid Meiosis I Meiosis II Diploid Haploid

49. 49 Meiosis I: Reduction Division Nucleus Spindlefibers Nuclearenvelope Early Prophase I (Chromosome number doubled) Late Prophase I Metaphase I Anaphase I Telophase I (diploid)

50. 50 Prophase I Early prophase Homologs pair. Homologs pair. Crossing over occurs Crossing over occurs. Late prophase Chromosomes condense. Chromosomes condense. Spindle forms. Spindle forms. Nuclear envelope fragments. Nuclear envelope fragments.

51. 51 Tetrads Form in Prophase I Homologous chromosomes (each with sister chromatids) Homologous chromosomes (each with sister chromatids) Join to form a TETRAD Called Synapsis

52. 52 Crossing-Over Homologous chromosomes in a tetrad cross over each other Homologous chromosomes in a tetrad cross over each other Pieces of chromosomes or genes are exchanged Pieces of chromosomes or genes are exchanged Produces Genetic recombination in the offspring Produces Genetic recombination in the offspring

53. 53 Homologous Chromosomes During Crossing-Over

54. 54 Crossing-over multiplies the already huge number of different gamete types produced by independent assortment Crossing-Over

55. 55 Metaphase I Homologous pairs of chromosomes align along the equator of the cell

56. 56 Anaphase I Homologs separate and move to opposite poles. Sister chromatids remain attached at their centromeres attached at their centromeres.

57. 57 Telophase I Nuclear envelopes reassemble. Spindle disappears. Cytokinesis divides cell into two.

58. 58 Meiosis II Only one homolog of each chromosome is present in the cell Only one homolog of each chromosome is present in the cell. Meiosis II produces gametes with one copy of each chromosome and thus one copy of each gene. Sister chromatids carry identical genetic information. Gene X

59. 59 Meiosis II: Reducing Chromosome Number Prophase II Metaphase II Anaphase II Telophase II 4 Identical haploid cells

60. 60 Prophase II Nuclear envelope fragments. Spindle forms.

61. 61 Metaphase II Chromosomes align along equator of cell.

62. 62 Anaphase II Sister chromatids separate and move to opposite poles Sister chromatids separate and move to opposite poles. Equator Pole

63. 63 Telophase II Nuclear envelope assembles. Chromosomes decondense. Spindle disappears. Cytokinesis divides cell into two.

64. 64 Results of Meiosis Gametes (egg & sperm) form Four haploid cells with one copy of each chromosome One allele of each gene Different combinations of alleles for different genes along the chromosome

65. 65 Gametogenesis Oogenesis or Spermatogenesis

66. 66 Spermatogenesis Occurs in the testes Occurs in the testes Two divisions produce 4 spermatids Two divisions produce 4 spermatids Spermatids mature into sperm Spermatids mature into sperm Men produce about 250,000,000 sperm per day Men produce about 250,000,000 sperm per day

67. 67 Spermatogenesis in the Testes Spermatid

68. 68Spermatogenesis

69. 69 Oogenesis Occurs in the ovaries Occurs in the ovaries Two divisions produce 3 polar bodies that die and 1 egg Two divisions produce 3 polar bodies that die and 1 egg Polar bodies die because of unequal division of cytoplasm Polar bodies die because of unequal division of cytoplasm Immature egg called oocyte Immature egg called oocyte Starting at puberty, one oocyte matures into an ovum (egg) every 28 days Starting at puberty, one oocyte matures into an ovum (egg) every 28 days

70. 70 Oogenesis in the Ovaries

71. 71 Oogenesis Oogonium(diploid) Mitosis Primaryoocyte(diploid) Meiosis I Secondaryoocyte(haploid) Meiosis II (if fertilization occurs) First polar body may divide (haploid)Polarbodiesdie Ovum (egg) Second polar body (haploid) a A X X a X A X a X a X Matureegg A X A X

72. 72 Comparing Mitosis and Meiosis

73. 73 MitosisMeiosis Number of divisions 12 Number of daughter cells 24 Genetically identical? YesNo Chromosome # Same as parent Half of parent Where Somatic cells Germ cells When Throughout life At sexual maturity Role Growth and repair Sexual reproduction Comparison of Divisions

74. 74