Mitosis - Cell division

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Mitosis - Cell division
http//www.youtube.com/watch?vVGV3fv-uZYI
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• Living organisms have life cycles.
• Life cycles begin with organisms formation,
  followed by growth and development and end in
  death.

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• Individual cells have life cycles.
• Some cells constantly complete the cycle, others
  take 16-20 hours or longer.
• Cell cycle is broken down into sections

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Interphase

• The longest part of a cells life cycle
• Several major things occur during Interphase
• The cell grows, develops.
• Organelles are duplicated.
• The DNA is copied (chromosomes duplicated)
• The cell prepares for cell division.
• Interphase is NOT part of mitosis.

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Interphase
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• In Interphase, chromatids are duplicated.
• When the nucleus is ready to divide, each
  duplicated chromosome coils into two thickened
  strands called chromatids.

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Mitosis

• Mitosis process in which the nucleus divides to
  form two identical nuclei.
• Steps of Mitosis Prophase, Metaphase, Anaphase,
  and Telophase. (PMAT)

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Prophase (Prepare)

• First step of mitosis
• Chromatids are fully visible under a microscope
• Nucleolus and nuclear membrane disintegrate
• Two organelles called centrioles move to
  opposite ends in the cell.
• Between the centrioles, (only in animal cells)
  thin threadlike structures called spindle fibers
  begin to stretch across the cell.

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Metaphase (Middle)

• The chromosomes line up across the midline of the
  cell.
• The centromere of each chromosome becomes
  attached to the spindle fibers.

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Anaphase (Apart)

• The centromere, in the center of each pair of
  chromatids, splits in half.
• The spindle fibers shorten, pulling the pair of
  chromatids apart.
• Each pair of chromatids separate, and move to
  opposite ends of the cell.

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Telophase (Two nuclei form)

• Spindle fibers disappear.
• Nuclear membrane reappears.
• Chromosomes begin to uncoil and a new nucleus
  forms.

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Cytokinesis

• Division of the cytoplasm
• In animal cells the cell membrane pinches in
  the middle.
• In plant cells a cell plate forms followed by
  the formation of new cell walls .
• Then cells enter into Interphase to repeat the
  cell cycle again.

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Cytokinesis
Animal Cell
Why doesnt a plant cell pinch in at the sides
like an animal cell?
Plant Cell
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Onion Root Tip Cells
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Results of Mitosis

• Mitosis is the division of a nucleus.
• The process produces two new nuclei that are
  identical to each other and to the original
  nucleus.

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Why does mitosis happen?

• Mitosis allows for
• Growth
• Replacement of worn out or damaged cells
• In some organisms, it is used to produce new
  organisms

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Asexual Reproduction

• A new organism is produced from one organism.
• The new organism has exactly the same hereditary
  material as the parent organism.

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Asexual Reproduction in Plants
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Asexual Reproduction in Animals
Budding and Regeneration
http//www.youtube.com/watch?v489CSop00sY
http//www.youtube.com/watch?vf7cXeWxxfD4
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(No Transcript)
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Prokaryotic organisms cannot undergo mitosis
(they have no nucleus) They reproduce asexually
using fission
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http//www.youtube.com/watch?vVGV3fv-uZYI
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What are the stages?

1. Interphase
2. Prophase
3. Metaphase
4. Anaphase
5. Telophase
6. Cytokinesis

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Identify each stage of the cell cycle(no
cytokinesis stage)
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Answers

1. Metaphase
2. Prophase
3. Telophase
4. Interphase
5. Interphase
6. Interphase
7. Anaphase
8. Interphase
9. Anaphase
10. Interphase

11. Metaphase 12. Telophase 13. Interphase 14.
Prophase 15. Interphase 16. Interphase 17.
Metaphase 18. Interphase Which stage is the
longest Interphase