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Cell Division

Cell Division

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Cell Division

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  1. Cell Division Section 8.2

  2. All cells are derived from the division of pre-existing cells • Cell division is the process by which cells produce offspring cells

  3. Cell division in Prokaryotes • Binary fission- the division of a prokaryotic cell into 2 offspring cells

  4. Cell division in Eukaryotes • Mitosis- results in new cells with genetic material that is identical to that of the original cell • Meiosis- reduces the chromosome number by half in new cells

  5. The cell cycle • The repeating set of events that make up the life of a cell • Interphase- the time between cell divisions • M phase- mitosis • Cytokinesis- the division of the cytoplasm of the cell

  6. Interphase • G1 phase-offspring cells grow to mature size • S phase- the cell’s DNA is copied • G2 phase- the time gap following the S phase and preceding cell division • G0 phase- cells do not copy their DNA and don’t prepare for cell division

  7. Mitosis • Divided into 4 phases: prophase, metaphase, anaphase, and telophase

  8. Prophase • First phase of mitosis • Centrosomes- appear next to the disappearing nucleus • Centrioles- found in animal cells

  9. Spindle fibers- made of microtubles radiate from the centrosomes in preparation for mitosis • Mitotic spindle- equally divides the chromatids between the 2 offspring cells

  10. Kinetochore fibers- attach to kinetochore • Kinetochore- disk-shaped protein • Polar fibers- extend across the dividing cell from centrosome to centrosome

  11. Metaphase • Second phase of mitosis • The kinetochore fibers move the chromosomes to the center of the dividing cell

  12. Anaphase • Third stage of mitosis • Chromatids of each chromosome separate at the centomere

  13. Telophase • Fourth stage of mitosis • Spindle fibers disassemble • Chromosomes return to a less tightly coiled chromatin state

  14. Cytokinesis • Cleavage furrow- pinches the cell into 2 cells (animal cells) Cell plate- membrane-bound cell wall (plant cells)