1. 1 Cellular Division copyright cmassengale

2. 2 Cell Division All cells are derived from pre- existing cells All cells are derived from pre- existing cells New cells are produced for growth and to replace damaged or old cells New cells are produced for growth and to replace damaged or old cells Differs in prokaryotes (bacteria) and eukaryotes (protists, fungi, plants, & animals) Differs in prokaryotes (bacteria) and eukaryotes (protists, fungi, plants, & animals) copyright cmassengale

3. 3 Keeping Cells Identical The instructions for making cell parts are encoded in the DNA, so each new cell must get a complete set of the DNA molecules copyright cmassengale

4. 4 DNA Replication DNA must be copied or replicated before cell division Each new cell will then have an identical copy of the DNA Original DNA strand Two new, identical DNA strands copyright cmassengale

5. 5 Identical Daughter Cells Parent Cell Two identical daughter cells copyright cmassengale

6. 6 Chromosomes

7. 7 Prokaryotic Chromosome DNA of prokaryotes (bacteria) is one, circular chromosome attached to the inside of the cell membrane DNA of prokaryotes (bacteria) is one, circular chromosome attached to the inside of the cell membrane copyright cmassengale

8. 8 Eukaryotic Chromosomes All eukaryotic cells store genetic information in chromosomes Most eukaryotes have between 10 and 50 chromosomes in their body cells (Somatic Cells) pairs Human body cells have 46 chromosomes or 23 identical pairs

9. 9 Eukaryotic Chromosomes Each chromosome is composed of a single, tightly coiled DNA molecule Chromosomes can’t be seen when cells aren’t dividing and are called chromatin

10. Eukaryotic Chromosome Structure Normally, chromosomes are spread out in a form called chromatin During mitosis, chromosomes fold up and condense

11. 11 Compacting DNA into Chromosomes DNA is tightly coiled around a set of 8 proteins called histones Nucleosome is 146 base pairs of DNA wrapped around the 8 histones

12. 12 Chromosomes in Dividing Cells Duplicated chromosomes are called chromatids Held together by the centromere Called Sister Chromatids

13. 13 Karyotype A picture of the chromosomes from a human cell arranged in pairs by size A picture of the chromosomes from a human cell arranged in pairs by size First 22 pairs are called autosomes First 22 pairs are called autosomes Last pair are the sex chromosomes Last pair are the sex chromosomes XX female or XY male XX female or XY male

14. 14 Boy or Girl? Y - Chromosome X - Chromosome The Y Chromosome Decides copyright cmassengale

15. 15 Cell Reproduction copyright cmassengale

16. 16 2 Types of Cell Reproduction 1.Asexual reproduction involves a single cell dividing to make 2 new, identical daughter cells Mitosis (eukaryotes) & binary fission (prokaryotes) are examples of asexual reproduction Mitosis (eukaryotes) & binary fission (prokaryotes) are examples of asexual reproduction 2.Sexual reproduction involves two cells (egg & sperm) joining to make a new cell (zygote) that is NOT identical to the original cells Meiosis (eukaryotes) is an example Meiosis (eukaryotes) is an example

17. 17 Cell Division in Prokaryotes copyright cmassengale

18. 18 Cell Division in Prokaryotes Prokaryotes (bacteria) divide into 2 identical cells by the process of binary fissionProkaryotes (bacteria) divide into 2 identical cells by the process of binary fission Parent cell 2 identical daughter cells Chromosome replicates Cell splits

19. 19 Prokaryotic Cell Undergoing Binary Fission copyright cmassengale

20. 20 Animation of Binary Fission copyright cmassengale

21. 21 The Cell Cycle copyright cmassengale

22. 22 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 collectively these 3 stages are called interphase M - mitosis M - mitosis C - cytokinesis C - cytokinesis copyright cmassengale

23. 23 Cell Cycle copyright cmassengale

24. 24 Interphase - G 1 Stage 1 st growth stage after cell division1 st growth stage after cell division Cells mature by making more cytoplasm & organellesCells mature by making more cytoplasm & organelles Cell carries on its normal metabolic activitiesCell carries on its normal metabolic activities copyright cmassengale

25. 25 Interphase – S Stage Synthesis stage Synthesis stage DNA is copied or replicated DNA is copied or replicated Two identical copies of DNA Original DNA

26. 26 Interphase – G 2 Stage 2 nd Growth Stage2 nd Growth Stage Occurs after DNA has been copiedOccurs after DNA has been copied All cell structures needed for division are made (e.g. centrioles)All cell structures needed for division are made (e.g. centrioles) Both organelles & proteins are synthesizedBoth organelles & proteins are synthesized

27. 27 Sketch the Cell Cycle Daughter Cells DNA Copied Cells Mature Cells prepare for Division Cell Divides into Identical cells copyright cmassengale

28. The Cell Cycle The length of time the cell cycle takes depends on the type of cell. –The more specialized the cell the less likely it is to divide. Nerve cells usually never divide, they enter G0

29. 29 Mitosis copyright cmassengale

30. Maintaining Chromosome Number mitosis, cytoplasmic division chromosome (unduplicated) in daughter cell at interphase chromosome (unduplicated) in daughter cell at interphase chromosome (unduplicated) in cell at interphase same chromosome (duplicated) in interphase prior to mitosis

31. 31 Mitosis Division of the nucleusDivision of the nucleus Also called karyokinesisAlso called karyokinesis Only occurs in eukaryotesOnly occurs in eukaryotes Has four stagesHas four stages

32. 32 Four Mitotic Stages 1.Prophase 2.Metaphase 3.Anaphase 4.Telophase copyright cmassengale

33. 33 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 copyright cmassengale

34. 34 Late Prophase Nuclear membrane & nucleolus are broken downNuclear membrane & nucleolus are broken down Chromosomes continue condensing & are clearly visibleChromosomes continue condensing & are clearly visible Spindle fibers called kinetochores attach to the centromere of each chromosomeSpindle fibers called kinetochores attach to the centromere of each chromosome Spindle finishes forming between the poles of the cellSpindle finishes forming between the poles of the cell

35. 35 Late Prophase Nucleus & Nucleolus have disintegrated Chromosomes

36. 36 Spindle Fiber attached to Chromosome Kinetochore Fiber Chromosome

37. 37 Review of Prophase What the cell looks like What’s happening

38. 38 Sketch The Spindle

39. 39 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 Pole of the Cell Equator of Cell

40. 40 Metaphase Chromosomes lined at the Equator Asters at the poles Spindle Fibers copyright cmassengale

41. 41 Metaphase Aster Chromosomes at Equator

42. 42 Review of Metaphase What the cell looks like What’s occurring copyright cmassengale

43. 43 Anaphase Sister chromatids are pulled apart to opposite poles of the cell Sister chromatids are pulled apart to opposite poles of the cell copyright cmassengale

44. 44 Anaphase Sister Chromatids being separated copyright cmassengale

45. 45 Anaphase Review What the cell looks like What’s occurring

46. 46 Telophase Sister chromatids at opposite poles Sister chromatids at opposite poles Spindle disassembles Spindle disassembles A new Nuclear envelope forms around each set of sister chromatids A new Nuclear envelope forms around each set of sister chromatids Nucleolus reappears Nucleolus reappears CYTOKINESIS occurs CYTOKINESIS occurs Chromosomes unwind to form chromatin Chromosomes unwind to form chromatin

47. 47 Comparison of Anaphase & Telophase

48. 48 Cytokinesis Means division of the cytoplasm Means division of the cytoplasm 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 In plant cells: cell plate forms In animal cells: cleavage furrow In animal cells: cleavage furrow

49. 49 Cytokinesis Cleavage furrow in animal cell Cell plate in plant cell

50. 50 Mitotic Stages

51. 51 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)

52. 52 Identical Daughter Cells Chromosome number the same, but cells smaller than parent cell What is the 2n or diploid number? 2

53. 53 Review of Mitosis copyright cmassengale

54. 54 Draw & Learn these Stages copyright cmassengale

55. 55 Draw & Learn these Stages copyright cmassengale

56. 56 Interphase Prophase Metaphase Anaphase Telophase Name the Mitotic Stages: Name this? copyright cmassengale

57. 57 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 copyright cmassengale

58. 58 Mitosis Animation Name each stage as you see it occur? copyright cmassengale

59. 59 Mitosis in Onion Root Tips Do you see any stages of mitosis? copyright cmassengale

60. 60 Test Yourself over Mitosis copyright cmassengale

61. 61 Mitosis Quiz copyright cmassengale

62. 62 Mitosis Quiz copyright cmassengale

63. 63 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 copyright cmassengale

64. 64 Identify the Stages Early, Middle, & Late Prophase Late Prophase MetaphaseAnaphase Late Anaphase Telophase Telophase & Cytokinesis ? ? ?? ? ?? copyright cmassengale

65. 65 Locate the Four Mitotic Stages in Plants Metaphase Prophase Anaphase Telophase copyright cmassengale

66. 66 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 copyright cmassengale

67. 67 Meiosis Formation of Gametes (Eggs & Sperm) copyright cmassengale

68. 68 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) copyright cmassengale

69. 69 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) copyright cmassengale

70. 70 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 copyright cmassengale

71. 71 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 copyright cmassengale

72. 72 Fertilization – “Putting it all together” 1n =3 2n = 6 copyright cmassengale

73. 73 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 copyright cmassengale

74. 74 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. copyright cmassengale

75. 75 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! copyright cmassengale

76. 76 Meiosis: Two Part Cell Division Homologsseparate Sisterchromatidsseparate Diploid Meiosis I Meiosis II Diploid Haploid copyright cmassengale

77. 77 Meiosis I: Reduction Division Nucleus Spindlefibers Nuclearenvelope Early Prophase I (Chromosome number doubled) Late Prophase I Metaphase I Anaphase I Telophase I (diploid) copyright cmassengale

78. 78 Prophase I Early prophase Homologs pair up. Homologs pair up. Tetrad forms and Crossing over occurs Tetrad forms and Crossing over occurs. Late prophase Chromosomes condense. Chromosomes condense. Spindle forms. Spindle forms. Nuclear envelope fragments. Nuclear envelope fragments. copyright cmassengale

79. 79 Tetrads Form in Prophase I Homologous chromosomes (each with sister chromatids) Homologous chromosomes (each with sister chromatids) Join to form a TETRAD Called Synapsis copyright cmassengale

80. 80 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 copyright cmassengale

81. 81 Crossing-over multiplies the already huge number of different gamete types produced by independent assortment Crossing-Over

82. 82 Metaphase I Homologous pairs of chromosomes align along the equator of the cell

83. 83 Anaphase I Homologs separate and move to opposite poles. Sister chromatids remain attached at their centromeres attached at their centromeres. copyright cmassengale

84. 84 Telophase I Nuclear envelopes reassemble. Spindle disappears. Cytokinesis divides cell into two. copyright cmassengale

85. 85 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 copyright cmassengale

86. 86 Meiosis II: Reducing Chromosome Number Prophase II Metaphase II Anaphase II Telophase II 4 Genetically Different haploid cells copyright cmassengale

87. 87 Prophase II Nuclear envelope fragments. Spindle forms. copyright cmassengale

88. 88 Metaphase II Chromosomes align along equator of cell. copyright cmassengale

89. 89 Anaphase II Sister chromatids separate and move to opposite poles Sister chromatids separate and move to opposite poles. Equator Pole copyright cmassengale

90. 90 Telophase II Nuclear envelope assembles. Chromosomes decondense. Spindle disappears. Cytokinesis divides cell into two. copyright cmassengale

91. 91 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 copyright cmassengale

92. 92 Meiosis Animation copyright cmassengale

93. 93 Gametogenesis Oogenesis or Spermatogenesis copyright cmassengale

94. 94 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 copyright cmassengale

95. 95 Spermatogenesis in the Testes Spermatid copyright cmassengale

96. 96Spermatogenesis copyright cmassengale

97. 97 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 copyright cmassengale

98. 98 Oogenesis in the Ovaries copyright cmassengale

99. 99 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 copyright cmassengale

100. 100 Comparing Mitosis and Meiosis copyright cmassengale

101. 101 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