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The Cell Cycle: A closer look! PowerPoint Presentation
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The Cell Cycle: A closer look!

The Cell Cycle: A closer look!

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The Cell Cycle: A closer look!

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  1. The Cell Cycle: A closer look! Biology 12

  2. Funny?

  3. Review (from last Class):

  4. Which stage is longest?

  5. Interphase • Aka the resting phase (but not really…) • Essentially, the cell is in between divisions and is carrying out maintenance activities of the cell • Made up of 3 sub-phases: • G1 phase • S phase • G2 phase

  6. Interphase: G1phase • 1st growth phase • Cell mature by making more cytoplasm & organelles • Cell carries on its normal metabolic activities, such as synthesising proteins

  7. Interphase: S phase • Synthesis stage • DNA is copied or replicated Two identical copies of DNA Original DNA

  8. Interphase: G2 phase • 2nd Growth Stage • Occurs after DNA has been copied • All cell structures needed for division are completed (e.g. centrioles) • Both organelles & proteins continue to be synthesized

  9. Mitosis • Aka karyokinesis • Division of the nucleus • Only occurs in eukaryotes • Made up of 4 phases: • Prophase • Metaphase • Anaphase • Telophase

  10. Mitosis: prophase • Early prophase: • Centrioles: make spindle fibres and move towards opposite plates • Chromosomes shorten and thicken (now visible under a microscope) • Late prophase: • Centrioles reach poles • Nuclear membrane (envelope) & nucleolus start to disappear

  11. Mitosis: Metaphase • Spindle fibres attach to centromeres • Sister chromatids (doubled chromosomes) line up at equator (middle of cell) • Guided by spindle fibers

  12. Mitosis: Anaphase • Centromeres divide in two • Spindle fibers contract and pull sister chromatids towards opposite ends of cell (pole) • Each pole (future daughter cells) will have an identical set of chromosomes

  13. Mitosis: telophase • Sister chromatids at opposite poles • Spindle disassembles • Nuclear membrane forms around each set of sister chromatids • Nucleolus reappears • Chromosomes loss their distinct outlines reappear as chromatin

  14. In pictures: • Prophase • Metaphase • Anaphase • Telophase

  15. Cytokinesis: • Means division of the cytoplasm • Division of cell into two, identical halves called daughter cells • Would this happen the same way in plants and animal cells? Why or why not? • In plant cells, cell plate forms at the equator to divide cell • In animal cells, cleavage furrow forms to split cell

  16. Cytokinesis Cleavage furrow in animal cell Cell plate in animal cell

  17. Helpful hint? • Interphase • Prophase • Metaphase • Anaphase • Telophase • Cytokinesis IPMATC

  18. Amimation: • http://www.youtube.com/watch?v=AhgRhXl7w_g&feature=fvsr

  19. To do: • Mitosis colouring sheet • Labelling sheet • Nelson Bio 11 Book • #1 to 9