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Mitosis

Mitosis. Why Mitosis?. The purpose of mitosis is to generate two new cells from one cell. The “daughter cells” generated are exact copies of the “parent cell” Mitosis is happening in many cells in your body as we speak! Some cells divide more frequently than others. Mitosis. Cytokinesis.

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Mitosis

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  1. Mitosis

  2. Why Mitosis? • The purpose of mitosis is to generate two new cells from one cell. • The “daughter cells” generated are exact copies of the “parent cell” • Mitosis is happening in many cells in your body as we speak! • Some cells divide more frequently than others

  3. Mitosis Cytokinesis Interphase Mitosis is part of the Cell Cycle

  4. Interphase Key Events in the Cell Cycle • The cell gets larger • Organelles are made • Genetic information is duplicated • Half of the DNA and organelles go to one end and the other half to the opposite end • The cell is split down the middle to make 2 new cells

  5. G2 Mitosis Cytokinesis G1 S Interphase • Gap1 (G1) • Preparation for growth • Organelles, membranes, and ribosomes made • Synthesis (S) • Chromosomes replicated • Gap2 (G2) • Preparation for division • Mitochondria divide • Remember, mitochondria have their own chromosome! Q4 Part 1

  6. Interphase Mitosis Key Events in the Cell Cycle • The cell gets larger • Organelles are made • Genetic information is duplicated • Half of the DNA and organelles go to one end and the other half to the opposite end • The cell is split down the middle to make 2 new cells Q7

  7. Nucleus of cell after mitosis Chromosomes are not duplicated Nucleus of cell after S phase Chromosomes are duplicated Homologous pair Chromosomes in Somatic Cells Nucleus of cell during G1 Chromosomes not duplicated

  8. Keep in Mind…

  9. Mitosis • Prophase • Metaphase • Anaphase • Telophase P M A T Cytokinesis Interphase

  10. Prophase • Pro =forward, forth • Chromosomes condense • Nuclear envelope breaks down • Membrane surrounding the nucleus • Centrioles move to opposite poles • Spindle fibers grow Q4 Part 2

  11. Metaphase • Meta =after, with • Chromosomes line up at the midline • Spindle attaches to chromosomes at the centromere • The centromere is where the sister chromatids are attached Q4 Part 2

  12. Anaphase • Ana =against • Centromeres split • Sister chromatids are pulled to opposite poles by the shortening of spindle fibers • Once separated, each sister chromatid is now a chromosome (and each is exactly like the chromosome found in the original cell before S of interphase) Q4 Part 2

  13. Telophase • Telo =completion of a goal • Spindle breaks down • Nuclear envelope forms in each of the daughter cells • Chromosomes decondense Q4 Part 2

  14. Interphase Mitosis Cytokinesis Key Events in the Cell Cycle • The cell gets larger • Organelles are made • Genetic information is duplicated • Half of the DNA and organelles go to one end and the other half to the opposite end • The cell is split down the middle to make 2 new cells Q7

  15. Cytokinesis Mitosis Cytokinesis Interphase • “Cell-making” phase • Organelles and cytoplasm are distributed between daughter cells • Microfilament band at equator contracts to pinch apart 2 new daughter cells

  16. Summary of Cell Cycle • Cell grows • DNA replicates • Organelles are made • Chromosomes condense • Chromosomes line up at the equator • Replicated chromosomes are pulled apart to opposite poles • Chromosomes decondense • Two daughter cells are formed G1 S G2 Prophase Metaphase Anaphase Telophase Cytokinesis

  17. IPee on the MAT, See? P M A T C I

  18. G2 Mitosis Cytokinesis G1 S Go • Resting phase • Cell may: • Enter S phase • Die • Cell is damaged • Do nothing • Neuron Go Cell Death Sit tight

  19. G2 Mitosis Cytokinesis G1 S Cell Cycle Checkpoints DNA damage checkpoints Spindle checkpoint

  20. Apoptosis • Programmed cell death • Neat and orderly

  21. Necrosis • Cell explodes • Not so neat and orderly • In response to injury

  22. Telomeres • Consist of a repeated sequence of DNA • Nature’s solution to the end-replication problem • Very tips of chromosomes cannot be replicated • Shortened with each mitotic division • Limits # of possible cell divisions • Cell will not divide after ~50 divisions • Not found in eggs/sperm, bone marrow cells, cancer cells • Shortening is hastened by chronic stress

  23. Cell Differentiation • The process whereby a cell becomes specialized • Every cell contains the exact same genetic information (all 23 chromosome pairs) • One chromosome from mom and one from dad • Not all genetic info is being used by every cell • Different cell types are making different proteins • The proteins being made by a cell give it specialized characteristics (e.g. blood cell vs. brain cell)

  24. Stem Cells • Important for regenerating cells that are lost (e.g. skin cells) and for growth • Stem cells are undifferentiated • Totipotent =able give rise to any cell type • Progenitor cells • Somewhat specialized • Pluripotent =able to produce many different cell types

  25. Pathways to Cell Specialization • Each specialized cell type uses only certain “recipes” from the “cookbook”

  26. Embryonic Stem Cells -IVF • Yields totipotent cells • Uses frozen embryos from in vitro fertilization • in vitro =in a dish • in vivo =in the body

  27. Embryonic Stem Cells –Nuclear Transfection

  28. Cloning

  29. Adult Stem Cells • Pluripotent • Found in bone marrow, umbilical cord blood, certain parts of the brain Even I have stem cells!

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