Chapter 8 Section 1

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Chapter 8 Section 1

• Cell Division and Mitosis

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Function

• Increase number of cells (growth)
• Replace dead cells
• One-celled organisms - reproduction

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Cell Cycle

• Interphase about 80 of cycle
• Mitosis about 15 of cycle
• Cytoplasm splits about 5 of cycle

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Interphase

• Cell grows, functions
• Organelles duplicate
• DNA copied
• Chromosomes duplicate
• Prepares for mitosis
• Next slide explains how.

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Interphase prep for mitosis

• Chromosomes duplicate
• 2 strands called chromatids
• Held together at centromere
• Centrioles move to opposite ends of cell.

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4 Next Steps of Mitosis

• 1. Prophase spindle fibers form on centrioles.
  Chromatids done.
• 3. Anaphase chromatids separate now called
  chromosomes again.

• 2. Metaphase chromatids lined up in center,
  attached to spindle fibers.

• 4. Telophase spindle fibers disappear, new
  nucleus forms.

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Cytoplasm divides

• Animal cells
• Membrane pinches

• Plant cells
• Cell plate forms
• New membranes form inside

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Results

• Identical cells

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Asexual Reproduction

• Cell division
• Fission bacteria (no nucleus)
• Runners (spider plants, strawberries)
• Cuttings (coleus)
• Budding (hydra)
• Regeneration (sponges, sea stars)