Functions of Neurotrophins NT4/5
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Questions and Answers

What happens to the number of motoneurons if a limb bud is removed from a chick embryo?

  • The number of motoneurons varies randomly.
  • The number of motoneurons remains the same.
  • The number of motoneurons increases.
  • The number of motoneurons decreases. (correct)
  • What effect does increasing the size of a limb target by transplanting an extra limb bud have on motoneuron death?

  • Causes random changes in motoneuron death.
  • Has no impact on motoneuron death.
  • Reduces motoneuron death. (correct)
  • Increases motoneuron death.
  • What is the main role of trophic factors in relation to neurons?

  • To induce neuronal migration.
  • To support neuron survival. (correct)
  • To stimulate axon growth.
  • To provoke apoptosis.
  • What is the function of Nerve Growth Factor (NGF) according to the text?

    <p>Support neuron survival and axon outgrowth.</p> Signup and view all the answers

    What happens if NGF function is disrupted in vivo according to the text?

    <p>Dramatic loss of neurons in the ganglion.</p> Signup and view all the answers

    Which statement best describes the role of neurotrophins?

    <p>Support neurons in both CNS and PNS.</p> Signup and view all the answers

    What effect does adding curare (a drug blocking muscle contractions) have on motoneurons?

    <p>Supports motoneuron survival.</p> Signup and view all the answers

    Which molecule is responsible for the trophic activity of Nerve Growth Factor (NGF)?

    <p>'Trophic' molecule</p> Signup and view all the answers

    Which neurotrophin binds all the TRKs?

    <p>NT3</p> Signup and view all the answers

    What is the function of p75 in response to neurotrophin binding?

    <p>Induces apoptosis</p> Signup and view all the answers

    How are all trks activated?

    <p>By heterodimerization</p> Signup and view all the answers

    Which adaptor protein binds to phosphorylated Shc after trkA activation?

    <p>Grb2</p> Signup and view all the answers

    What is the role of Akt in promoting cell survival?

    <p>Inhibiting apoptosis by activating Bcl2</p> Signup and view all the answers

    Which protein inhibits apoptosis by promoting the exchange of GDP for GTP bound to Ras?

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

    What is the main outcome of injecting DNA for activated MEK into PC12 cells?

    <p>Protein synthesis + neurite growth</p> Signup and view all the answers

    What happens when neurotrophins regulate the ras/raf/mek/erk kinase cascade?

    <p>Regulation of neurite outgrowth</p> Signup and view all the answers

    What is the primary function of downstream effector proteins in neurotrophin signaling pathways?

    <p>Regulation of cell survival and growth processes</p> Signup and view all the answers

    What characterizes the binding affinity between neurotrophins and p75 receptor?

    <p>All neurotrophins bind with similar affinity</p> Signup and view all the answers

    What are the 4 classic morphological features characteristic of apoptosis?

    <p>Cell and nuclear shrinkage, chromatin condensation, cellular fragmentation, phagocytosis of cell remains</p> Signup and view all the answers

    What is the purpose of apoptosis during development according to the text?

    <p>To sculpt the final tissue structure by removing unnecessary cells</p> Signup and view all the answers

    Which process involves an active biochemical program leading to cell death often referred to as 'cell suicide'?

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

    How was apoptosis first imaged according to the text?

    <p>By electron microscopy (EM)</p> Signup and view all the answers

    Which term describes cell death resulting from traumatic injury involving rapid cell lysis?

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

    What was the significance of the first experiments performed to prove apoptosis as an active biochemical process?

    <p>They indicated that protein synthesis is needed for apoptosis</p> Signup and view all the answers

    What process involves balancing the number of neurons with the amount of target that needs to be innervated in the nervous system?

    <p><em>Programed Cell Death (PCD): Apoptosis</em></p> Signup and view all the answers

    How does apoptosis contribute to sculpting the final tissue structure during development?

    <p>By removing unnecessary cells after overproduction.</p> Signup and view all the answers

    In apoptosis, what happens to the cell during the process?

    <p>The cell takes itself apart and packages itself into vesicles called apoptotic bodies.</p> Signup and view all the answers

    Why did the first experiments using mRNA/protein synthesis inhibitors help prove apoptosis as an active biochemical process?

    <p>They blocked apoptosis which indicated a need for protein synthesis.</p> Signup and view all the answers

    Which family member inhibits ced-4 to prevent caspase cleavage?

    <p>ced-9</p> Signup and view all the answers

    What is considered the 'point of no return' in apoptotic cell death?

    <p>Caspase activation</p> Signup and view all the answers

    Where does neurotrophin signaling occur due to retrograde transport of a vesicle carrying the trk receptor?

    <p>Cell body</p> Signup and view all the answers

    Which hormone readily crosses the blood-brain barrier and regulates gene expression by translocating to the nucleus?

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

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