Mitosis Section 9'3

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Mitosis (Section 9.3)

• Mr. Gawles Biology Class
• January 2006

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Mitosis Background

• Stage of cell cycle where the cell divides
• This process is unique to eukaryotes
• There are two main processes in mitosis
• Mitosis (nucleus and duplicated chromosomes
  divide and are even distributed into two
  daughter nuclei)
• Divided into prophase, metaphase, anaphase, and
  telophase
• Cytokinesis (process where cytoplasm is divided
  into two.begins before mitosis is completed)
• THE GOAL OF MITOSIS
• Produce two genetically identical daughter cells
  each has the same number of chromosomes as parent
  cell
• REMEMBER This is how the genetic material in
  the nucleus is passed on to offspring cells!!!!
  

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Why is Mitosis Important?

• A process of cell division in which genetic
  information is distributed equally to identical
  daughter cells in eukaryotes
• Each daughter cell is provided with the same
  instructions needed to carry out life processes
• Process responsible for the growth of plants,
  animals, and fungi.
• From zygote to YOU!
• Responsible for cell repair
• Responsible for reproduction in prokaryotes

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Stages of Mitosis

• Prophase (occurs right after the end of
  interphase)
• Metaphase
• Anaphase
• Telophase/Cytokinesis
• JUST REMEMBERPMAT

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Interphase

• NOT part of mitosishappens before and after!
• Individual chromosomes NOT visible
• DNA is in the form of loosely packed chromatin
• Presence of nucleolus indicates the cell is still
  producing ribosomes in preparation for division
• See images..

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Interphase Images
nucleolus
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Prophase

• First and longest phase
• Nucleolus disappears and the nuclear envelope
  breaks down
• Spindle starts to form
• Chromatin fibers condense (Chromosomes become
  visible) and move toward center of cell
• Chromatids attach to spindle

Ascaris sp.
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Metaphase

• Shortest phase
• Chromosomes attach to the spindle and line up in
  the middle of the cell
• The spindle is now fully formed

Ascaris sp.
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Anaphase

• Centromeres holding sister chromatids
  split(sister chromatids separate)
• Microtubules shorten pulling identical daughter
  chromosomes towards opposite poles of the cell

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Telophase

• Telophase begins when daughter chromosomes arrive
  at poles
• Processes of prophase reverse1. Spindle
  disappears 2. Nuclear membrane re-forms around
  each new nucleus 3. Chromosomes unfold again
  into chromatin4. Nucleoli reappear

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Cytokinesis

• The cytoskeleton constricts cell and pinches
  off the cytoplasm
• The cytoplasm and its contents is thus divided
  into two individual daughter cells
• Each daughter cell receives one nucleus and about
  half the cytoplasm
• Each daughter cell is provided with the same
  instructions needed to carry out life
  processesthis is how life begets life.
• After telophase/cytokinesis daughter cells return
  to interphase
• NOTE Cell plate forms in plants but NOT animals

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Check out Online Activity 9.3
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Mitosis Images
http//www.bio.miami.edu/dana/250/mitosis.jpg
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Mitosis Vocabulary

• Microtubules
• Hollow tubes made up of proteins that act as
  train tracks along which organelles and other
  cellular objects can move
• Spindle
• Made up of microtubules and yet another protein
• Guide chromosomes along train tracks
• Centrioles
• Organizational sites for microtubules
• During division, move to opposite ends of the
  cell and appear to aid with separation of the
  chromosomes
• Plants dont have centrioles

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What stage?
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What stage?
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What stage?
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What stage?
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What stage?
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Practice?

• Click here
• Click here for more nice images
• FANTASTIC ONION TIPS MITOSIS IMAGES
• Click here for labeled images
• Online Activity 9.3 page 3 has good practice too!

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Animations to Check Out

• BBC TV Animation
• John Kyrk Animation
• Cells Alive Animation of Mitosis
• Mitosis with 6 chromosomes
• Another nice animation with a quiz
• Another nice animation
• Practice Mitosis