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Cell Cycle and Mitosis

Cell Cycle and Mitosis

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Cell Cycle and Mitosis

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  1. Cell Cycle and Mitosis 9.1 Cell Cycle

  2. What is the cell cycle? • Repeating series of events • Five stages • Interphase (3 parts) • G1 • S • G2 • M phase (2 parts) • Mitosis • Cytokinesis

  3. What happens in Interphase? • G1 • Normal growth • Recovery from last mitotic division • S • Replication of chromatids • G2 • Synthesis of proteins for mitosis

  4. Cell Cycle and Mitosis 9.2 M phase: Mitosis and cytokinesis

  5. What happens during the M phase? • Mitosis • Prokaryotes undergo binary fission instead • Cytokinesis

  6. What is a chromosome? • Length of DNA with genes and noncoding regions • Highly condensed version of chromatin • Heterochromatin vs. euchromatin

  7. What is mitosis? • Division of nuclear material • Duplicated chromosomes are split • This creates unduplicated chromosomes • Chromosome terminology • Sister chromatids • Kinetechore • Centromere • Diploid (2n) vs. haploid (1n)

  8. What are the stages of mitosis? • Prophase • Prometphase • Metaphase • Anaphase • Telophase

  9. What happens in prophase? • Nuclear envelope disappears • Centrioles move apart • Nucleous disappears • Chromatin condenses to form chromosomes • Recall that these are duplicated

  10. What happens during prometaphase? • Kinetechores appear • Spindles attach • Polar spindle fibers extend and overlap

  11. What happens during metaphase? • Duplicated chromosomes align along metaphase plate

  12. What happens during anaphase? • Sister chromatids pulled apart • Chromosomes are now unduplicated

  13. What happens during telophase? • Reverse of prophase • Cleavage furrow develops in animal cells

  14. What is the second part of the M phase? • Cytokinesis • Cytoplasmic division • Animal cells • Contractile ring • Plant cells • Cell plate

  15. Cell Cycle and Mitosis 9.3 Cell cycle control and cancer

  16. Why do cells undergo mitosis? • Repair and replacement • Apoptosis of somatic cells • blebbing • Stem cells • Serve as reservoir for replacing old cells

  17. What controls the cell cycle? • Checkpoints • G1 • Apoptosis if DNA is damaged • G2 • M

  18. What is cancer? • Uncontrolled cell growth • Characteristics • Neoplasms (tumors) • Benign vs. malignant • Angiogenesis • Metastasis • Abnormal nuclei • Undifferentiated (anaplasia) • Lack contact inhibition • No apoptosis

  19. How does cancer occur? • Mutations of cell repair genes • Activation of telomerase • Mutations of either/both • Proto-oncogenes • Become oncogenes • Tumor suppressor cells

  20. What are proto-oncogenes? • “gas pedal” of cell division • Mutated oncogene • Examples • ras genes • rasN (leukemia) • BRCA1

  21. What are tumor suppressor genes? • Brake pedal of cell division • If mutated  loss of cell cycle control • Examples • p53 gene • RB gene