Cell Growth and Cell Cycle

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Cell Growth and Cell Cycle
2013-02-20 13:59:20

Advanced Higher Biology - Unit One - Cell growth and cell cycle
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  1. How do eukaryote cells reproduce?
    Cell division
  2. The cell cycle can be split into two.  What are these two?
    • Interphase
    • Mitosis/nuclear division and cytokinesis/cytoplasmic division
  3. What is interphase?
    This is when the cell contents are built up.  It is a period of growth and metabolism.
  4. Name and describe the three sections can interphase be split up into?
    • G1 - First growth stage.  The cell grows, makes proteins and copies organelles.
    • S phase.  When DNA replication occurs.
    • G2 - Second growth stage.  The cell grows, makes more proteins and copies of organelles.
  5. Describe the stages of mitosis
    • Prophase - The chromosomes condense and become visable as two joined chromatids.  Spindle fibres attach to the chromosomes at the centromere.  The nuclear membrane disintegrates.
    • Metaphase - Spindle fibres move the chromosomes so they line up on the metaphase plate at the equator of the cell.
    • Anaphase - spindle fibres shorten and pull sister chromatids apart to different poles.  Once separated the chromatids are called chromosomes.
    • Telophase - The separated chromosomes are pulled apart by the spindle fibres to opposite poles to form daughter nuclei.  The chromosomes start to uncoil and a nuclear membrane forms around each group of chromosomes.
  6. Describe cytokinesis (cytoplasmic division)
    Cell membrane is pinched in by the cytoskeleton, forming a furrow which slices into the centre of the cell, dividing the cytoplasm and cell into two daughter cells with the same number of chromosomes.  Plant cells form a middle lamella and cell wall before the membrane is made.
  7. What is a miotic index?  What does it shows?
    The miotic index is the percentage of cells in a sample undergoing mitosis.  It shows how much growth is occuring in a tissue
  8. What is the formula to work out the miotic index?
    (Number of cells undergoing mitosis / Total number of cells) x 100