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  • 1. The Cell Cycle and Cellular Reproduction Chapter 9 Mader: Biology 8 th Ed.
  • 2. Interphase
    • Most of the cell cycle is spent in interphase.
      • G 1 - Cell doubles its organelles and accumulates materials needed for DNA synthesis.
      • S - DNA replication.
      • G 2 - Cell synthesizes proteins necessary for cell division.
    Mader: Biology 8 th Ed.
  • 3. Mitotic Stage
    • Cell division stage that includes mitosis (nuclear division or karyokinesis) and cytokinesis (cytoplasm division).
    Mader: Biology 8 th Ed.
  • 4. Cell Cycle Mader: Biology 8 th Ed. G O
  • 5. Cell Cycle Control
    • Regulated by external signals (e.g., growth factors) and internal signals
    • Researchers have identified internal signal protein (cyclin) that increases and decreases as cell cycle continues.
    Mader: Biology 8 th Ed.
  • 6. Cell Cycle Control
    • Cyclins
      • Must be present for the cell to proceed from the G 2 stage to the M stage and from G 1 stage to S stage.
        • Allows time for any damage to be repaired.
    Mader: Biology 8 th Ed.
  • 7. Cell Cycle Control Mader: Biology 8 th Ed. Signaling protein p53; stop to repair damage OR apoptosis
  • 8. Apoptosis
    • Programmed cell death (or cell suicide)
      • Normal part of development
      • Protects against cancer
    Mader: Biology 8 th Ed. 9 week embryo froglet
  • 9. Apoptosis
      • Cells have enzymes (caspases) necessary for apoptosis to occur.
        • Ordinarily held in check by inhibitors, but can be unleashed by internal or external signals.
    • Mitosis increases and apoptosis decreases the number of somatic cells.
    Mader: Biology 8 th Ed.
  • 10. Mader: Biology 8 th Ed. Apoptosis
  • 11. Chromosomes
    • When a eukaryotic cell is
    • not undergoing division,
    • the DNA within the
    • nucleus is a tangled
    • mass of chromatin.
      • DNA wraps around
      • histones
      • Condenses into chromosomes
        • (6 ft of DNA in each human cell)
    Mader: Biology 8 th Ed.
  • 12. Chromosomes
    • Each species has a characteristic number of chromosomes.
      • Diploid (2n) - Two of each kind.
      • Haploid (1n) - One of each kind.
    Mader: Biology 8 th Ed.
  • 13. Mitosis
    • During mitosis, a diploid nucleus divides to produce diploid daughter nuclei.
      • Two identical chromatids are called sister chromatids .
        • Attached to each other at centromere.
          • During nuclear division, sister chromatids separate at the centromeres, and each duplicated chromosome gives rise to two daughter chromosomes.
    Mader: Biology 8 th Ed.
  • 14. Duplicated Chromosomes Mader: Biology 8 th Ed. Each chromosome as it passes through cell cycle… G1 phase S phase End of mitosis one copy of info DNA replicated; Sister chromatids separate; 2 copies of info Each cell has 1 copy of info Centromere 1 sister chromatid
  • 15. Mitosis in Animal Cells
    • Each centrosome in an animal cell contains a pair of barrel-shaped organelles (centrioles) and an array of short microtubules (aster).
      • http://www.biostudio.com/d_%20Mitosis.htm
    Mader: Biology 8 th Ed.
  • 16. Mitosis in Animal Cells
    • Prophase
      • Chromatin has condensed.
      • Nucleolus disappears.
      • Nuclear envelope disintegrates.
      • Spindle begins to assemble.
    • Prometaphase
      • Kinetochores develop on centromere.
        • Attach sister chromatids to spindle fibers.
    Mader: Biology 8 th Ed.
  • 17. Mader: Biology 8 th Ed.
  • 18. Mitosis in Animal Cells
    • Metaphase
      • Chromosomes, attached to kinetochore fibers, are in alignment at center of cell.
    • Anaphase
      • Sister chromatids split, producing daughter chromosomes.
        • Daughter chromosomes are pulled to opposite poles.
    Mader: Biology 8 th Ed.
  • 19. Mitosis in Animal Cells
    • Telophase
      • Spindle disappears as new nuclear envelopes form around the daughter chromosomes.
        • Chromosomes become diffuse chromatin again.
        • Nucleolus appears in each daughter nucleus.
    Mader: Biology 8 th Ed.
  • 20. Mader: Biology 8 th Ed.
  • 21. Cytokinesis
    • Cytokinesis accompanies mitosis in most cells, but not all.
      • Mitosis without cytokinesis results in a multinucleated cell.
        • Begins in anaphase, continues in telophase, but does not reach completion until the following interphase begins.
    Mader: Biology 8 th Ed.
  • 22. Cytokinesis
    • Animal Cells
      • Cleavage furrow, membrane indentation between daughter nuclei, begins as anaphase nears completion.
        • Deepens when a band of actin filaments (contractile ring) forms a circular constriction between the two daughter cells.
    Mader: Biology 8 th Ed.
  • 23. Cytokinesis in Animal Cells Mader: Biology 8 th Ed.
  • 24. Plant Cell Division
    • Meristematic plant tissue retains the ability to divide throughout the plant’s life.
      • Found at root and shoot tips.
    Mader: Biology 8 th Ed.
  • 25. Phases of Mitosis in Plant Cells Mader: Biology 8 th Ed.
  • 26. Cytokinesis
    • Plant Cells
      • Rigid cell wall of plant cells does not permit cytokinesis by furrowing.
        • Begins with formation of a cell plate which eventually becomes new plasma membrane between the daughter cells.
    Mader: Biology 8 th Ed.
  • 27. The Cell Cycle and Cancer
    • Cancer is a growth disorder that results from the mutation of genes regulating the cell cycle.
      • Carcinogenesis , development of cancer, tends to be gradual.
    Mader: Biology 8 th Ed.
  • 28. Mader: Biology 8 th Ed.
  • 29. Characteristics of Cancer Cells
    • Lack differentiation.
    • Have abnormal nuclei.
    • Form tumors.
      • Loss of contact inhibition.
    • Undergo metastasis.
      • New tumors distant from primary tumor.
    • Undergo angiogenesis.
      • Formation of new blood vessels.
    Mader: Biology 8 th Ed.
  • 30. Mader: Biology 8 th Ed.
  • 31. Origin of Cancer
    • Mutations in DNA repair mechanisms.
    • Mutations to proto-oncogenes.
      • Proto-oncogenes become oncogenes.
    • Mutations to tumor-suppressor genes.
      • Includes p53
    • Telomerase allows cancer cells to continually divide.
      • Telomere = tip of chromosome that is shortened with each cell division
      • Telomerase MAINTAINS telomeres
    Mader: Biology 8 th Ed.
  • 32. Prokaryotic Cell Division
    • Asexual Reproduction - offspring are genetically identical to the parent.
      • Binary fission produces two (binary) daughter cells that are identical to the original parent.
        • Prokaryotes contain a single chromosome with only a few proteins.
        • ( E. coli has about 4,000 genes. Humans have about 25,000 genes.)
    Mader: Biology 8 th Ed.
  • 33. Binary Fission Mader: Biology 8 th Ed.