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The Cell Cycle

The Cell Cycle. ie Mitosis & the like…. Cell Division: Key Roles. Genome: cell’s genetic information Somatic cells – all cells except sex cells Gametes (sex cells): sperm & egg cells Chromosomes: DNA molecules Diploid (2n): 2 sets of chromosomes Haploid (1n): 1 set of chromosomes

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The Cell Cycle

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  1. The Cell Cycle • ie • Mitosis & the like….

  2. Cell Division: Key Roles • Genome: cell’s genetic information • Somatic cells – all cells except sex cells • Gametes (sex cells): sperm & egg cells • Chromosomes: DNA molecules • Diploid (2n): 2 sets of chromosomes • Haploid (1n): 1 set of chromosomes • Chromatin: DNA-protein complex • Chromatids: replicated strands of a chromosome • Centromere: joined part of chromatids • Mitosis: nuclear division • Cytokinesis: cytoplasm division • Meiosis: gamete cell division

  3. The Cell Cycle • Interphase 90% (or more) of cycle • G1 phase~ growth • S phase~ synthesis of DNA • G2 phase~ preparation for cell division • Mitotic phase: Mitosis~ nuclear division Cytokinesis~ cytoplasm division

  4. Mitosis • Prophase • Prometaphase • Metaphase • Anaphase • Telophase

  5. Prophase • Chromosomes visible • Nucleoli disappear • Sister chromatids • Centrosomes move apart as spindle forms Animation

  6. Prometaphase • Nuclear membrane fragments • Spindle Fibers are now at opposite ends and are beginning to interact with chromosomes • Kinetochore develops Animation

  7. Metaphase • Centrosomes at opposite poles • Centromeres are aligned in the “Metta” • IMPORTANT: • Chromosomes are not in any particular order. • Kinetochores of sister chromatids attached to microtubules (spindle) Animation

  8. Anaphase • Paired centromeres separate; sister chromatids liberated • Chromosomes move to opposite poles • Each pole now has a complete set of chromosomes • Cell begins to elongate Animation

  9. Telophase • Daughter nuclei form • Nuclear envelopes arise • Chromatin becomes less coiled • Two new nuclei complete mitosis Animation

  10. Cytokinesis • Cytoplasmic division • Animals: cleavage furrow • Plants: cell plate WebLink

  11. Cell Cycle regulation • Growth factors • PDGF: • “platelet derived Growth Factor” • Density-dependent inhibition • Anchorage dependence

  12. Cancer • Transformation • Tumor: benign or malignant • Metastasis

  13. So what’s the deal with KINASES???? • Kinases are Protein enzymes that control the cell cycle • Active when connected to cyclin proteins (Cyclin dependent kinases – Cdk) • Specific kinases give the go ahead signal at G1 and G2 checkpoints • Ex: High MPF (mitosis promoting factor) triggers mitosis, BUT active MPF degrades cyclin *So the MPF turns itself off by activating an enzyme that destroys cyclin, the cell then enters G1

  14. So what’s the deal with KINASES????

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