Cell Division

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Cell Division
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GOAL To make cells w/ SAME amount of DNA
1. Interphase
Cell copies DNA
2. Mitosis
Divides DNA Equally
3. Cytokinesis
Cytoplasm divides/Cell splits
BIG PICTURE Cell Division of Human Cells
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Why do cells divide?

• To create new life
• zygote divides to become ball of cells

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Why do cells divide?
Rarely divides

• To replace old cells
• Different cells divided at different rates

How fast do Cells divide?
Divides once/day
Never divides
Rarely divides
Divides once/year
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Why do cells divide?

• To help an organism grow
• adding cells makes organism bigger

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Why do cells divide?

• To heal from injury
• new cells fill in to help repair

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Learning Terms
Thin/Stringy DNA seen in interphase
Tightly coiled DNA Seen in mitosis
Exact copies
centromere
Chromosome
Duplicated Chromosome
Chromatin
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Interphase

• THINK! What 2 things happen
• during interphase?
• Cell grows
• Cell copies (doubles) its DNA

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Mitosis (4 Phases)

• The cell divides the DNA molecules equally
• THINK! A mosquito normally has 6 DNA molecules.
  How many molecules will each cell have after
  mitosis?
• THINK! Humans normally have 46 DNA molecules.
  How many molecules will each cell have after
  mitosis?

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46
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Phase 1 Prophase (P Prepare)

• Chromatin coils into chromosomes
• Nucleus disappears
• Spindle fibers appear

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Phase 2 Metaphase (M Middle)

• Spindle fibers move the duplicated chromosomes
  into the middle of the cell

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Phase 3 Anaphase (AApart)

• Duplicated chromosomes split at the centromere
• Spindle fibers pull chromosomes to opposite sides
  of the cell

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Phase 4 Telophase (T Tear/Two Nuclei)

• Chromosomes uncoil into chromatin
• Nucleus reappears
• Spindle fibers disappear

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Cytokinesis

• THINK! What happens?
• Cytoplasm and organelles divided (cell splits)

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Cytokinesis Animal vs. Plant

• Animal Cells
• Cell membrane pinches inward
• Plant Cells
• Hard Cell plate forms in center

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Visualizing Mitosis!

• ACTIVITY
• INTERACTIVE ACTIVITY TO TRY WITH THE CLASS!
• Mitosis Hybrid Medical Animation
• http//hybridmedicalanimation.com/anim_mitosis.htm
  l
• Mitosis with Music
• http//www.loci.wisc.edu/outreach/bioclips/
  CDBio.html
• Brain-Pop Clip (Mitosis)
• http//glencoe.mcgraw-hill.com/sites/007877
  800x/student_view0/brainpop_movies.html
• Streaming Animations
• Glencoe Mitosis Animation
• United Streaming (Mitosis_ 118)
• Real-Time Animations
• Animal Cell Mitosis (Just click on LIVE ANIMAL
  MITOSIS)