Cell Division

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Cell Division

• B-2.6 Summarize the characteristics of the cell
  cycle interphase (called G1, S, G2) the phases
  of mitosis (called prophase, metaphase, anaphase,
  and telophase) and plant and animal cytokinesis.

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The Cell Cycle

• Draw a large circle on your page
• Divide into 4 parts like this

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Interphase G1 Phase (Growth) S Phase
(Synthesis) G2 Phase (Growth) M Phase
(Mitosis) Prophase Metaphase Anaphase Telophas
e Cytokinesis
C
M
A
T
P
G1
G2
S
G0
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The Cell Cycle
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The Cell Cycle
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INTERPHASE

• G1 Phase
• Cell grows, makes proteins
• S Phase
• DNA replicates (synthesizes)
• G2 Phase
• Growing, getting ready for cell division

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INTERPHASE
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M Phase MITOSIS

• Prophase
• Chromatin condenses into chromosomes, becomes
  visible
• Nuclear membrane disappears
• Centrioles separate to opposite poles
• Spindle fibers form, grow toward center
• Longest phase (50-60 of mitosis)

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Prophase
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A little about CHROMOSOMES

• In Interphase, DNA in long thin threads, called
  CHROMATIN. Here, in S phase, they duplicate
  (replicate, synthesize)
• As Prophase begins, CHROMATIN winds up
  (condenses) into Chromosomes.
• Made of two sister Chromatids, joined at the
  Centromere.

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A duplicated chromosome
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This is interphases chromatin, long thin strands
of proteins and DNA. Only later in mitosis
beginning, Prophase, will this condense and coil
up into the classic looking X shaped structures,
termed chromosomes.
Coiled chromosomes
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M Phase MITOSIS

• Metaphase
• Chromosomes line up at cells equator
• Spindle fibers connect to chrom.
• Shortest phase of mitosis

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Metaphase
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M Phase MITOSIS

• Anaphase
• Centromeres that join the sister chromatids split
• Sister chromatids separate, becoming individual
  chrom.
• They now move to opposites sides of cell

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Anaphase
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M Phase MITOSIS

• Telophase
• Chromosomes uncoil, disappear
• Nuclear envelope reforms
• Spindle fibers break down
• Cytokinesis begins

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Telophase
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M Phase MITOSIS

• Cytokinesis Cytoplasm division
• In animals, cleavage furrow pinches cell in two.
• In plants, a cell plate forms, becoming the new
  wall.

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Cytokinesis animal
Cleavage furrow
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Cytokinesis plants
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M Phase MITOSIS
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Practice