Genetic basis of life(mitosis and meiosis)


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Genetic basis of life(mitosis and meiosis)

  1. 1. Cell Reproduction
  2. 2. Stem Cell Shakes In The News
  3. 3. Dividing Nuclear Material <ul><li>Cells must accurately separate genetic material during cell reproduction </li></ul><ul><li>Methods </li></ul><ul><ul><li>Mitosis </li></ul></ul><ul><ul><li>Meiosis </li></ul></ul>
  4. 4. Mitosis <ul><li>Produces two identical cells </li></ul><ul><li>Each cell has full DNA complement </li></ul><ul><li>Used for growth and repair of somatic cells </li></ul>
  5. 5. Meiosis <ul><li>Produces 4 cells from parent cell </li></ul><ul><li>Daughter cells have half genetic complement </li></ul><ul><li>Produces gametes (sex cells) </li></ul>
  6. 7. Animal Life Cycle <ul><li>Egg = female gamete </li></ul><ul><li>Sperm = male gamete </li></ul><ul><li>Zygote </li></ul><ul><ul><li>Fusion of egg & sperm </li></ul></ul><ul><ul><li>Full complement of genetic material </li></ul></ul>
  7. 8. Diploid Cells (2N) <ul><li>Full genetic complement </li></ul><ul><li>23 pair of chromosomes in humans </li></ul>
  8. 9. Haploid Cells (N) <ul><li>Produced during meiosis </li></ul><ul><li>Contain only one set of chromosomes </li></ul><ul><li>Reduction of chromosomes allows for combination to form diploid zygote </li></ul>
  9. 10. Fertilization <ul><li>One sex cell from each parent joins </li></ul><ul><li>Creates diploid zygote </li></ul><ul><li>Process is called sexual reproduction </li></ul>
  10. 11. Animal Life Cycles <ul><li>Diploid phase dominates </li></ul><ul><li>Gametes live hours to days </li></ul>
  11. 12. Plant Life Cycles <ul><li>Most have multicellular haploid phase </li></ul><ul><li>Phase names </li></ul><ul><ul><li>Gametophyte = haploid </li></ul></ul><ul><ul><li>Sporophyte = diploid </li></ul></ul><ul><li>Either phase can dominate, depending on plant type </li></ul>
  12. 14. Single Cell Eukaryote Reproduction <ul><li>Reproduce by mitosis </li></ul><ul><li>Called asexual reproduction </li></ul><ul><li>Produced two identical organisms </li></ul>
  13. 15. Asexual Reproduction <ul><li>All single cell eukaryotes </li></ul><ul><li>Some plants </li></ul><ul><li>Some animals </li></ul>
  14. 17. Cell Cycle
  15. 18. Interphase <ul><li>Most of cell cycle </li></ul><ul><li>Cell grows </li></ul><ul><li>Organelles replicated </li></ul><ul><li>DNA replicated </li></ul><ul><li>Readies for mitosis </li></ul><ul><li>Condenses DNA </li></ul>
  16. 19. G 1 Interphase <ul><li>Cell growth </li></ul><ul><li>Normal life functions </li></ul>
  17. 20. S Interphase <ul><li>DNA replicated </li></ul>
  18. 21. G 2 Interphase <ul><li>DNA condenses into chromosomes </li></ul><ul><ul><li>Strands = sister chromatids </li></ul></ul><ul><ul><li>Chromatids connected by centromere </li></ul></ul>
  19. 22. Stages of Mitosis <ul><li>Prophase </li></ul><ul><li>Metaphase </li></ul><ul><li>Anaphase </li></ul><ul><li>Telophase </li></ul>
  20. 23. Prophase <ul><li>Chromosomes shorten & thicken </li></ul><ul><li>Nucleolus disappears </li></ul>
  21. 24. Prophase <ul><li>Spindle fibers formed from microtubules </li></ul><ul><li>Microtubules surround microtubule-organizing center (centrosome) </li></ul><ul><li>Chromosomes begin to move apart </li></ul>
  22. 25. Metaphase <ul><li>Pairs of sister chromatids align at center </li></ul><ul><ul><li>Forms metaphase plate </li></ul></ul>
  23. 26. Anaphase <ul><li>Chromatids separate at centromere </li></ul><ul><li>Chromatids pulled in two directions </li></ul><ul><li>Chromosomes move toward poles </li></ul><ul><li>Equally divides hereditary material </li></ul>
  24. 27. Telophase <ul><li>Cell readied for division </li></ul><ul><li>Spindle fibers disassemble </li></ul><ul><li>Nuclear envelope reforms </li></ul><ul><li>Nucleolus reappears </li></ul>
  25. 28. Cytokinesis <ul><li>Cell division after mitosis </li></ul><ul><li>Cleavage furrow enlarges </li></ul>
  26. 29. Animal Cytokinesis <ul><li>Cell pinched in two </li></ul><ul><li>Pinching by microfilaments contracting </li></ul>
  27. 30. Plant Cytokinesis <ul><li>New cell wall must be laid down </li></ul><ul><li>Cell plate forms </li></ul>
  28. 31. Mitosis
  29. 32. Cancer <ul><li>Deregulation of cell cycle </li></ul><ul><li>Loss of control of mitosis </li></ul><ul><li>Result of mutation </li></ul><ul><li>Over 200 types </li></ul>
  30. 33. United States Cancer Death Rates
  31. 34. Characteristics of Cancer <ul><li>Uncontrolled cell growth </li></ul><ul><li>Loss of cell differentiation </li></ul><ul><li>Invasion of normal tissues </li></ul><ul><li>Metastasis = spread </li></ul>
  32. 38. Stages of Cancer <ul><li>Initiation </li></ul><ul><li>Promotion </li></ul><ul><li>Progression </li></ul>
  33. 39. Initiation of Cancer Transformation <ul><li>Series of gene mutations </li></ul><ul><li>Proto-oncogenes become oncogenes </li></ul><ul><li>Usually additional mutations are needed </li></ul><ul><ul><li>Affect tumor suppressor genes </li></ul></ul><ul><ul><li>Turn off cell “off” switch </li></ul></ul>
  34. 40. Promotion of Cancer <ul><li>Cells are stimulated to grow & divide </li></ul><ul><li>Carcinogens – initiate & promote cancer </li></ul><ul><ul><li>Viruses </li></ul></ul><ul><ul><li>Chemicals </li></ul></ul><ul><ul><li>Radiation </li></ul></ul><ul><li>Benign cells </li></ul><ul><ul><li>Masses of partially transformed cells </li></ul></ul><ul><ul><li>Cells exhibit displasia </li></ul></ul>
  35. 41. Normal Cells Dysplastic Cells
  36. 42. Progression of Cancer <ul><li>Cells become less differentiated </li></ul><ul><li>Cells invade other tissue </li></ul><ul><li>Move to other areas of the body </li></ul><ul><li>Called malignant cells </li></ul>
  37. 44. Meiosis <ul><li>Chromosome number halved </li></ul><ul><ul><li>2N  N </li></ul></ul><ul><li>Required for sexual reproduction </li></ul><ul><li>Starts with diploid parents </li></ul>
  38. 45. Homologues <ul><li>Homologous chromosomes </li></ul><ul><li>2 chromosomes, same linear gene sequence </li></ul>
  39. 46. Process of Meiosis <ul><li>Two stages: </li></ul><ul><li>Meiosis I </li></ul><ul><li>Meiosis II </li></ul><ul><li>Results in 4 haploid daughter cells </li></ul>
  40. 47. Meiosis I <ul><li>Splitting homologous pairs </li></ul><ul><li>Pairs line up = synapsis </li></ul>
  41. 48. Meiosis I <ul><li>Cross over – non sister chromosomes may cross over one another </li></ul><ul><li>Chromatids may exchange segments </li></ul>
  42. 49. Stages of Meiosis I
  43. 50. Interkinesis <ul><li>Interphase-like period </li></ul><ul><li>Between meiosis I and meiosis II </li></ul><ul><li>No DNA replication </li></ul>
  44. 51. Meiosis II Stages
  45. 52. Meiosis
  46. 53. Importance of Meiotic Recombination <ul><li>Provides variability for offspring </li></ul><ul><li>Essential to process of evolution </li></ul>
  47. 56. End chapter 12