Mitosis

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Mitosis
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Mitosis some basics

• form of nuclear division
• ? Therefore, only occurs in eukaryotic cells
• (prokaryotes perform binary fission)

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Mitosis

• Occurs in organisms for the purpose of
• ?
• ?
• ?
• ?

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Mitosis

• Goal

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Hardest Concept!! Homolog Homolog
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Cooler View!
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Interphase

• Not technically part of mitosis
• Cell spends gt90 time in this phase
• DNA exists in ___________ form
• Cell performs..?
• Most important Fact

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Prophase

• Events of Prophase

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Prophase

• Is the cell to the left a human cell?
• How many chromosomes are pictured?
• Are the chromosomes normal size or duplicated?
• Which pieces of DNA are identical to each other?

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Metaphase

• The duplicated chromosomes line up along the
  equator of the cell.
• What causes them to move?

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Metaphase

• How many chromosomes are pictured?
• Are the two red Xs identical to each other?

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Anaphase

• Spindle fibers split the duplicated chromosomes
  in half.
• The identical chromatids are separated from each
  other. But now they are normal sized
  chromosomes!
• Will the two daughter cells be genetically
  identical?

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Telophase

• Telophase is called reverse prophase because..

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Telophase

• In telophase, cytokinesis occurs.
• Cytokinesis -

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Telophase

• Q Are the two daughter cells genetically
  identical to each other????
• Clones -

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VI. Cytokinesis - division of the cytoplasm
A. In animal cells a contracting ring of
microfilaments tightens to form a
cleavage furrow
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B. In plant cells a cell plate forms between
daughter cells
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Quick-Check Identify the phase
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IV. The Cell Cycle
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Interphase (90 of the cell cycle) can be
subdivided into
1. G1 (Gap 1) is a time of growth
just after division.
2. S (Synthesis) is when the chromosomes
replicate.
3. G2 (Gap 2) is a period of additional growth
and preparation for division.
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Thought Question

• When do you think a stimulus which results in DNA
  replication would occur?

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MITOSIS BIG IDEAS

• Occurs in all eukaryotic organisms
• Each chromosome is copied. (Can you describe
  how?)One copy of every chromosome is distributed
  to each of the two new daughter cells.
• Thus ? All body (somatic) cells contain full set
  of chromosomes (therefore full set of genes)

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Questions

• When do cells mitose?
• What determines when cells start and stop
  mitosing?
• Can you think of a medical condition in which you
  would like human cells to mitosis, (but they
  normally dont)?