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2010 Fall Bio 317 Exam 3

B together with stanley cohen she discovered and

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Unformatted text preview: lls. c) She implanted chick embryos with sponge-soaked NGF and found that peripheral ganglia were greatly reduced in size and could not send out axons. d) She discarded as trivial and unimportant, the finding by Elmer Beuker that sarcoma tumors had growth-promoting effects on chick peripheral neurons. e) She found that PC12 cells responded to NGF in the same way as neurons. 3) The following is true of the range of NGF actions. a) Primary cultures of peripheral neurons showed that the elaboration of neuronal phenotype was an intrinsic property of the neurons and resulted as a secondary consequence of NGF-mediated survival. b) PC12 cells illustrated that NGF could stimulate axon growth, neurotransmitter synthesis, electrical excitability, and the expression of neuronal genes in vitro. c) NGF cannot influence synaptic efficacy in the adult. d) NGF is necessary for the survival of most non-neuronal tissues during early development. e) None of the above. 4) The following is NOT true of a major NGF-stimulated signaling pathway. a) Injection of anti-Ras antibody into PC12 cells resulted in a stimulation of axon growth by NGF. b) The NGF receptor, Trk, was first discovered as an oncogene formed by the fusion of tropomyosin with an orphan receptor tyrosine kinase. c) Ras activation results in the stimulation of a protein kinase cascade involving Raf, Mek and Erk kinases. d) Rap activation mediates the sustained activation of Erk kinase. e) None of the above. 5) The following is true of NGF and EGF signaling in neurons: a) Only the NGF pathway activates both Ras and Erk kinase. b) Only EGF engages proto-oncogenes in its signaling pathway. c) Only NGF/Trk endosomes can mediate signaling. d) NGF uses two different adaptors, Shc and FRS2, which engage the same site on Trk receptors and stimulate two pathways that converge on Mek and Erk signaling. e) Only EGF mediates sustained signaling of Erk kinase. 6) The following are examples of how NGF signaling can mediate a wide range of actions in neurons: a) The Trk receptor stimulates both Ras...
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