lecture 8
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Questions and Answers

What is the primary role of the zone of polarizing activity (ZPA) in the limb bud?

  • Inducing mirror-image duplications in grafted limb buds (correct)
  • Causing cyclopia in newborn lambs
  • Expressing Sonic hedgehog in the nervous system
  • Converting anterior limb bud tissue into tissue with polarizing activity

    • What effect does retinoic acid have on Sonic hedgehog expression in the anterior limb bud?

  • It inhibits Sonic hedgehog expression
  • It has no effect on Sonic hedgehog expression
  • It induces Sonic hedgehog expression (correct)
  • It causes limb duplications

    • What is the relationship between the gene Sonic hedgehog and the Drosophila segment polarity gene hedgehog?

  • They both have similar effects on the nervous system
  • Sonic hedgehog is related to the Drosophila segment polarity gene hedgehog (correct)
  • Sonic hedgehog can polarize limbs in grafting experiments, whereas hedgehog cannot
  • Sonic hedgehog is unrelated to hedgehog

    • What effect does the overexpression of the endosomal protein Rab5c have on the Fgf8 gradient?

    <p>It yields a steeper and shorter Fgf8 gradient</p> Signup and view all the answers

    What is the impact of inhibiting endocytosis with the dominant negative GTPase dynamin on the Fgf8 gradient?

    <p>It causes a shallower and longer Fgf8 gradient</p> Signup and view all the answers

    Which mechanism influences the amount of Fgf8 protein ultimately secreted from a producing cell?

    <p>The difference in the rate of fgf8 transcription and fgf8 mRNA decay</p> Signup and view all the answers

    What are the major sources of pluripotent stem cells from the early embryo?

    <p>Embryonic stem cells (ESCs) and embryonic germ cells</p> Signup and view all the answers

    Where do the intestinal stem cell (ISC) and progenitors reside?

    <p>At the base of the crypts</p> Signup and view all the answers

    What was sufficient to increase both vasculature and the population of neural progenitors in an old mouse?

    <p>Administering GDF11 into the circulatory system</p> Signup and view all the answers

    What factors are involved in inducing ectoderm lineages from ESCs?

    <p>Wnt and Bmp4</p> Signup and view all the answers

    How are ESCs induced to become primitive streak-like cells for mesoderm or endoderm lineages?

    <p>By activating paracrine factors like Wnt and Bmp4</p> Signup and view all the answers

    What is the role of the four transcription factors in the process of inducing pluripotency in iPS cells?

    <p>Converting cells to a pluripotent state</p> Signup and view all the answers

    What is the purpose of injecting hematopoietic progenitor and stem cells into the original mouse?

    <p>To cure the sickle-cell anemia in the mouse</p> Signup and view all the answers

    What distinguishes iPS cells?

    <p>They are distinctive in shape</p> Signup and view all the answers

    What are the key factors used to differentiate ESCs into the cell types of each germ layer?

    <p>Paracrine factors and transcription factors</p> Signup and view all the answers

    What is the primary role of morphogens?

    <p>Inducing dramatic morphogenetic changes</p> Signup and view all the answers

    In the context of lipid modifications, which molecule is highlighted in the text?

    <p>Notum</p> Signup and view all the answers

    What is the significance of wint in regulating cell signaling pathways?

    <p>It is associated with cell signaling pathways like Sonic hedgehog and lipid modifications</p> Signup and view all the answers

    What do the cells on the top of the dorsal ventral axis line versus the cells on the bottom of the line dictate?

    <p>Whether they contribute to the back side of the wing or the eventual side of the wing</p> Signup and view all the answers

    What will cells more distal from the middle of the wing give rise to?

    <p>The most distal parts of the wing</p> Signup and view all the answers

    What happens if a specific factor called swim is mutated?

    <p>Unknown</p> Signup and view all the answers

    What is the role of the gene distal-less in the formation of appendages?

    <p>It is crucial for distal formation and distal identity of appendages</p> Signup and view all the answers

    What happens to the broad domain of the downstream factor activation in the swim mutant?

    <p>It becomes further restricted due to improper dispersion of wing molecules</p> Signup and view all the answers

    What is the function of the fgfa molecules produced by cells in the experiment?

    <p>Promoting proper activation of distal cells in the wing</p> Signup and view all the answers

    What happens to cells as they become more differentiated?

    <p>They become less responsive</p> Signup and view all the answers

    What type of cells are homatoportic stem cells?

    <p>Stem cells that give rise to various blood cells</p> Signup and view all the answers

    What do early factors enable super potent stem cells to do?

    <p>Maintain their potency</p> Signup and view all the answers

    What is the trajectory of cells as they become less responsive and more autonomous?

    <p>They become locked in</p> Signup and view all the answers

    What is one way to connect back to conditional and autonomous specification?

    <p>By discussing the factors relevant at different stages</p> Signup and view all the answers

    In what state are cells less able to be conditioned on their cellular context?

    <p>Differentiated state</p> Signup and view all the answers

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