Mitosis

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Mitosis

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In The Beginning One

• Most of the organisms we see started out as one
  cell
• Humans start out as a single cell, the zygote,
  formed by uniting a sperm and egg
• The zygote divides to make approximately one
  trillion cells
• During the process of dividing, cells become
  specialized to function in the various tissues
  and organs of the body
• Mitosis is the process of cell division in
  eukaryotic cells

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Why Cells Must Divide

• In multi-celled organisms (like humans) cells
  specialize for specific functions thus the
  original cells must divide to produce different
  kinds of cells
• Cells can only take in nutrients and excrete
  waste products over the surface of the membrane
  that surrounds them. The surface to volume ratio
  decreases with the square of the volume (unless
  special accommodations are made)

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The Cell Lifecycle

• The cell lifecycle is well defined and can be
  divided into four stages
• Gap 1 (G1) - The growth phase in which most cells
  are found most of the time
• Synthesis (S) - During which new DNA is
  synthesized
• Gap 2 (G2) - The period during which no
  transcription or translation occurs and final
  preparations for division are made
• Mitosis - Cell division

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The Cell Life Cycle
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Stages Of Mitosis

• During mitosis an exact copy of the genetic
  material in the mother cell must be distributed
  to each daughter cell
• Each stage of mitosis is designed to achieve
  equal and exact distribution of the genetic
  material which has been copied during the S phase
  of the cell cycle

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Stages Of Mitosis

• Interphase - The in between stage - Originally
  metaphase was thought to be a resting stage now
  we know that this is the stage most cells spend
  their time in doing the things that cells do and,
  if they are preparing to divide, growing and
  replicating their DNA

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Interphase

• Growth
• Normal Cell Function
• Over 2/4 of cells life
• DNA replication

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Prophase

• Centrioles move to opposite side of cell
• DNA is condensed into chromosomes
• Nucleus disappears

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Metaphase

• Chromosomes line up at equator of spindle
• Mustache Stage

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Anaphase

• Chromosomes pull apart
• Move towards opposite ends of the cell

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Telophase

• Chromosomes arrive at the poles of the cells
• Cytoplasm splits

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Cytokenesis

• Complete division of cell membrane
• Cell plate meets cell wall (in plants)

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Stages Of Mitosis
Mother cell
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Animations

• http//www.cellsalive.com/mitosis.htm
• http//www.johnkyrk.com/mitosis.html
• http//hybridmedicalanimation.com/anim_mitosis_wmV
  ideo.html

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Mitosis Picture Test

• Identify each stage of mitosis that these cells
  are in.

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Number One
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Number Two
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Number Three
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Number Four
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Number Five
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Number Six