Chapter 21 The Genetic Basis of Development

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Chapter 21The Genetic Basis of Development
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Chapter 21The Genetic Basis of Development

• Embryonic development involves
• Cell division
• Cell differentiation
• Morphogenesis

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Chapter 21The Genetic Basis of Development

• Model organisms

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Chapter 21The Genetic Basis of Development

• Model organisms

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Chapter 21The Genetic Basis of Development

• Model organisms

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Chapter 21The Genetic Basis of Development

• Model organisms

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Chapter 21The Genetic Basis of Development

• Model organisms

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Chapter 21The Genetic Basis of Development

• Different kinds of cells have the same DNA

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Chapter 21The Genetic Basis of Development

• Different kinds of cells have the same DNA.
• Totipotent able to divide to produce an entire
  new organism (most plant cells, some animal
  cells).

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Chapter 21The Genetic Basis of Development

• Different kinds of cells have the same DNA.
• Pluripotent able to reproduce and differentiate
  in vitro and in vivo (stem cells).

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Chapter 21The Genetic Basis of Development

• Different kinds of cells make different proteins
  thru regulation of gene transcription

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Chapter 21The Genetic Basis of Development

• Different kinds of cells make different proteins
  thru regulation of gene transcription.
• Regulation is directed by maternal molecules in
  the cytoplasm and by signals from neighboring
  cells.

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Chapter 21The Genetic Basis of Development

• Pattern formation development of spatial
  organization

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Chapter 21The Genetic Basis of Development

• Pattern formation development of spatial
  organization.
• Continuous in plants, but for animals it takes
  place only in embryos and juveniles

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Chapter 21The Genetic Basis of Development

• Pattern formation development of spatial
  organization.
• Continuous in plants, but for animals it takes
  place only in embryos and juveniles.
• Positional information along axes and in relation
  to neighbors.

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Chapter 21The Genetic Basis of Development

• Life Cycle of Drosophila

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Chapter 21The Genetic Basis of Development

• Life Cycle of Drosophila
• 1. For the first ten cell divisions, there is no
  cell growth and no cytokinesis. You end up with
  one big multinucleated cell.

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Chapter 21The Genetic Basis of Development

• Life Cycle of Drosophila
• 2. At the tenth division, nuclei migrate to the
  periphery of the embryo.

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Chapter 21The Genetic Basis of Development

• Life Cycle of Drosophila
• 3. At division 13, plasma membranes finally
  begin to partition the 6000 or so nuclei into
  separate cells. The body plan and segments are
  already determined.

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Chapter 21The Genetic Basis of Development

• Life Cycle of Drosophila
• 4. Visible segments form. They look very much
  alike.

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Chapter 21The Genetic Basis of Development

• Life Cycle of Drosophila
• 5. Some cells move to new positions. Organs
  form. The worm-like larva hatches.
• The larva eats, grows, and molts through three
  larval stages.

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Chapter 21The Genetic Basis of Development

• Life Cycle of Drosophila
• 6. The larva forms a pupa in an enclosed case.

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Chapter 21The Genetic Basis of Development

• Life Cycle of Drosophila
• 7. Metamorphosis occurs inside the pupa. When
  the adult hatches, each segment is anatomically
  distinct.

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Chapter 21The Genetic Basis of Development

• Egg polarity genes

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Chapter 21The Genetic Basis of Development

• Egg polarity genes are maternal effect genes

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Chapter 21The Genetic Basis of Development

• Egg polarity genes are maternal effect genes.
• They produce proteins called morphogens

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Chapter 21The Genetic Basis of Development

• Egg polarity genes are maternal effect genes.
• They produce proteins called morphogens.
• A morphogen gradient establishes the
  anterior-posterior axis.

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Chapter 21The Genetic Basis of Development

• Bicoid is a gene in the mother that produces a
  two-tailed offspring.

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Chapter 21The Genetic Basis of Development

• Segmentation genes act in a cascade, directing
  the formation of segments

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Chapter 21The Genetic Basis of Development

• Segmentation genes act in a cascade, directing
  the formation of segments.
• Their products are transcription factors for
  other genes.

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Chapter 21The Genetic Basis of Development

• Segmentation genes act in a cascade, directing
  the formation of segments.
• Their products are transcription factors for
  other genes.

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Chapter 21The Genetic Basis of Development

• Homeotic genes control the growth of specific
  organs.

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Chapter 21The Genetic Basis of Development

• gene function
• maternal effect egg polarity
• segmentation
• gap coarse subdivision
• pair-rule further subdivision
• segment polarity orientation of segs
• homeotic specific organs

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Chapter 21The Genetic Basis of Development

• gene function
• maternal effect egg polarity

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Chapter 21The Genetic Basis of Development

• gene function
• maternal effect egg polarity
• mutation

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Chapter 21The Genetic Basis of Development

• gene function
• gap coarse subdivision

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Chapter 21The Genetic Basis of Development

• gene function
• gap coarse subdivision
• mutation

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Chapter 21The Genetic Basis of Development

• gene function
• pair-rule further subdivision

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Chapter 21The Genetic Basis of Development

• gene function
• pair-rule further subdivision
• mutation

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Chapter 21The Genetic Basis of Development

• gene function
• segment polarity further subdivision

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Chapter 21The Genetic Basis of Development

• gene function
• segment polarity further subdivision
• mutation

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Chapter 21The Genetic Basis of Development

• gene function
• homeotic specific organs

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Chapter 21The Genetic Basis of Development

• gene function
• homeotic specific organs
• mutation

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Chapter 21The Genetic Basis of Development

• Homeobox (hox) genes have been highly conserved

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Chapter 21The Genetic Basis of Development

• Homeobox (hox) genes have been highly conserved.

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Chapter 21The Genetic Basis of Development

• Neighboring cells instruct other cells to form
  particular structures

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Chapter 21The Genetic Basis of Development

• Neighboring cells instruct other cells to form
  particular structures.
• nematode
• 
  gonad
• 
  vulva

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Chapter 21The Genetic Basis of Development

• 
  gonad
• 
  vulva

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Chapter 21The Genetic Basis of Development

• 
  gonad
• epidermis
  vulva
• outer vulva
• inner vulva

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Chapter 21The Genetic Basis of Development

• 
  anchor cell
• precursor cells

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Chapter 21The Genetic Basis of Development

• The anchor cell secretes a first inducer

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Chapter 21The Genetic Basis of Development

• The anchor cell secretes a first inducer.
• The inducer binds to receptors on the nearest
  cell (where the concentration is highest)

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Chapter 21The Genetic Basis of Development

• The anchor cell secretes a first inducer.
• The inducer binds to receptors on the nearest
  cell (where the concentration is highest).
• That cell begins to develop into the inner vulva

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Chapter 21The Genetic Basis of Development

• The inner vulva cell secretes a second inducer

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Chapter 21The Genetic Basis of Development

• The inner vulva cell secretes a second inducer.
• The second inducer binds to receptors on
  neighboring cells

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Chapter 21The Genetic Basis of Development

• The inner vulva cell secretes a second inducer.
• The second inducer binds to receptors on
  neighboring cells.
• They begin to develop into outer vulva.

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Chapter 21The Genetic Basis of Development

• If you surgically remove the anchor cell from the
  embryo, the nematode develops without a vulva.