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Cell Reproduction

Cell Reproduction. Stem Cell Shakes In The News. Dividing Nuclear Material. Cells must accurately separate genetic material during cell reproduction Methods Mitosis Meiosis. Mitosis. Produces two identical cells Each cell has full DNA complement

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Cell Reproduction

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  1. Cell Reproduction

  2. Stem Cell ShakesIn The News

  3. Dividing Nuclear Material • Cells must accurately separate genetic material during cell reproduction • Methods • Mitosis • Meiosis

  4. Mitosis • Produces two identical cells • Each cell has full DNA complement • Used for growth and repair of somatic cells

  5. Meiosis • Produces 4 cells from parent cell • Daughter cells have half genetic complement • Produces gametes (sex cells)

  6. Animal Life Cycle • Egg = female gamete • Sperm = male gamete • Zygote • Fusion of egg & sperm • Full complement of genetic material

  7. Diploid Cells (2N) • Full genetic complement • 23 pair of chromosomes in humans

  8. Haploid Cells (N) • Produced during meiosis • Contain only one set of chromosomes • Reduction of chromosomes allows for combination to form diploid zygote

  9. Fertilization • One sex cell from each parent joins • Creates diploid zygote • Process is called sexual reproduction

  10. Animal Life Cycles • Diploid phase dominates • Gametes live hours to days

  11. Plant Life Cycles • Most have multicellular haploid phase • Phase names • Gametophyte = haploid • Sporophyte = diploid • Either phase can dominate, depending on plant type

  12. Single Cell Eukaryote Reproduction • Reproduce by mitosis • Called asexual reproduction • Produced two identical organisms

  13. Asexual Reproduction • All single cell eukaryotes • Some plants • Some animals

  14. Cell Cycle

  15. Interphase • Most of cell cycle • Cell grows • Organelles replicated • DNA replicated • Readies for mitosis • Condenses DNA

  16. G1 Interphase • Cell growth • Normal life functions

  17. S Interphase • DNA replicated

  18. G2 Interphase • DNA condenses into chromosomes • Strands = sister chromatids • Chromatids connected by centromere

  19. Stages of Mitosis • Prophase • Metaphase • Anaphase • Telophase

  20. Prophase • Chromosomes shorten & thicken • Nucleolus disappears

  21. Prophase • Spindle fibers formed from microtubules • Microtubules surround microtubule-organizing center (centrosome) • Chromosomes begin to move apart

  22. Metaphase • Pairs of sister chromatids align at center • Forms metaphase plate

  23. Anaphase • Chromatids separate at centromere • Chromatids pulled in two directions • Chromosomes move toward poles • Equally divides hereditary material

  24. Telophase • Cell readied for division • Spindle fibers disassemble • Nuclear envelope reforms • Nucleolus reappears

  25. Cytokinesis • Cell division after mitosis • Cleavage furrow enlarges

  26. Animal Cytokinesis • Cell pinched in two • Pinching by microfilaments contracting

  27. Plant Cytokinesis • New cell wall must be laid down • Cell plate forms

  28. Mitosis

  29. Cancer • Deregulation of cell cycle • Loss of control of mitosis • Result of mutation • Over 200 types

  30. United States Cancer Death Rates

  31. Characteristics of Cancer • Uncontrolled cell growth • Loss of cell differentiation • Invasion of normal tissues • Metastasis = spread

  32. Stages of Cancer • Initiation • Promotion • Progression

  33. Initiation of CancerTransformation • Series of gene mutations • Proto-oncogenes become oncogenes • Usually additional mutations are needed • Affect tumor suppressor genes • Turn off cell “off” switch

  34. Promotion of Cancer • Cells are stimulated to grow & divide • Carcinogens – initiate & promote cancer • Viruses • Chemicals • Radiation • Benign cells • Masses of partially transformed cells • Cells exhibit displasia

  35. Normal Cells Dysplastic Cells

  36. Progression of Cancer • Cells become less differentiated • Cells invade other tissue • Move to other areas of the body • Called malignant cells

  37. Meiosis • Chromosome number halved • 2N  N • Required for sexual reproduction • Starts with diploid parents

  38. Homologues • Homologous chromosomes • 2 chromosomes, same linear gene sequence

  39. Process of Meiosis Two stages: Meiosis I Meiosis II Results in 4 haploid daughter cells

  40. Meiosis I • Splitting homologous pairs • Pairs line up = synapsis

  41. Meiosis I • Cross over – non sister chromosomes may cross over one another • Chromatids may exchange segments

  42. Stages of Meiosis I

  43. Interkinesis • Interphase-like period • Between meiosis I and meiosis II • No DNA replication

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