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Chapter 21 The Genetic Basis of Development

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Title: Chapter 21 The Genetic Basis of Development


1
Chapter 21The Genetic Basis of Development
2
Chapter 21The Genetic Basis of Development
  • Embryonic development involves
  • Cell division
  • Cell differentiation
  • Morphogenesis

3
Chapter 21The Genetic Basis of Development
  • Model organisms

4
Chapter 21The Genetic Basis of Development
  • Model organisms

5
Chapter 21The Genetic Basis of Development
  • Model organisms

6
Chapter 21The Genetic Basis of Development
  • Model organisms

7
Chapter 21The Genetic Basis of Development
  • Model organisms

8
Chapter 21The Genetic Basis of Development
  • Different kinds of cells have the same DNA

9
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).

10
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).

11
Chapter 21The Genetic Basis of Development
  • Different kinds of cells make different proteins
    thru regulation of gene transcription

12
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.

13
Chapter 21The Genetic Basis of Development
  • Pattern formation development of spatial
    organization

14
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

15
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.

16
Chapter 21The Genetic Basis of Development
  • Life Cycle of Drosophila

17
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.

18
Chapter 21The Genetic Basis of Development
  • Life Cycle of Drosophila
  • 2. At the tenth division, nuclei migrate to the
    periphery of the embryo.

19
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.

20
Chapter 21The Genetic Basis of Development
  • Life Cycle of Drosophila
  • 4. Visible segments form. They look very much
    alike.

21
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.

22
Chapter 21The Genetic Basis of Development
  • Life Cycle of Drosophila
  • 6. The larva forms a pupa in an enclosed case.

23
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.

24
Chapter 21The Genetic Basis of Development
  • Egg polarity genes

25
Chapter 21The Genetic Basis of Development
  • Egg polarity genes are maternal effect genes

26
Chapter 21The Genetic Basis of Development
  • Egg polarity genes are maternal effect genes.
  • They produce proteins called morphogens

27
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.

28
Chapter 21The Genetic Basis of Development
  • Bicoid is a gene in the mother that produces a
    two-tailed offspring.

29
Chapter 21The Genetic Basis of Development
  • Segmentation genes act in a cascade, directing
    the formation of segments

30
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.

31
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.

32
Chapter 21The Genetic Basis of Development
  • Homeotic genes control the growth of specific
    organs.

33
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

34
Chapter 21The Genetic Basis of Development
  • gene function
  • maternal effect egg polarity

35
Chapter 21The Genetic Basis of Development
  • gene function
  • maternal effect egg polarity
  • mutation

36
Chapter 21The Genetic Basis of Development
  • gene function
  • gap coarse subdivision

37
Chapter 21The Genetic Basis of Development
  • gene function
  • gap coarse subdivision
  • mutation

38
Chapter 21The Genetic Basis of Development
  • gene function
  • pair-rule further subdivision

39
Chapter 21The Genetic Basis of Development
  • gene function
  • pair-rule further subdivision
  • mutation

40
Chapter 21The Genetic Basis of Development
  • gene function
  • segment polarity further subdivision

41
Chapter 21The Genetic Basis of Development
  • gene function
  • segment polarity further subdivision
  • mutation

42
Chapter 21The Genetic Basis of Development
  • gene function
  • homeotic specific organs

43
Chapter 21The Genetic Basis of Development
  • gene function
  • homeotic specific organs
  • mutation

44
Chapter 21The Genetic Basis of Development
  • Homeobox (hox) genes have been highly conserved

45
Chapter 21The Genetic Basis of Development
  • Homeobox (hox) genes have been highly conserved.

46
Chapter 21The Genetic Basis of Development
  • Neighboring cells instruct other cells to form
    particular structures

47
Chapter 21The Genetic Basis of Development
  • Neighboring cells instruct other cells to form
    particular structures.
  • nematode

  • gonad

  • vulva

48
Chapter 21The Genetic Basis of Development

  • gonad

  • vulva

49
Chapter 21The Genetic Basis of Development

  • gonad
  • epidermis
    vulva
  • outer vulva
  • inner vulva

50
Chapter 21The Genetic Basis of Development

  • anchor cell
  • precursor cells

51
Chapter 21The Genetic Basis of Development
  • The anchor cell secretes a first inducer

52
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)

53
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

54
Chapter 21The Genetic Basis of Development
  • The inner vulva cell secretes a second inducer

55
Chapter 21The Genetic Basis of Development
  • The inner vulva cell secretes a second inducer.
  • The second inducer binds to receptors on
    neighboring cells

56
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.

57
Chapter 21The Genetic Basis of Development
  • If you surgically remove the anchor cell from the
    embryo, the nematode develops without a vulva.
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