2009 Exam2key - NERVOUS SYSTEM II 080.306 SPRING 2009...

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NERVOUS SYSTEM II 080.306 SPRING 2009 SECOND EXAM I affirm that I have neither given nor received help from any student during the period of this exam. Signed ________________________________ Name (Print) ________________________________
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1) a)What are the major steps for nervous system development? (5 pts) 1. Proliferation 3. Differentiation 4. Axon Growth 5. Synapse Formation 6. Regressive Events b) Programmed cell death is a critical regressive process during nervous system development. At which developmental stage or time, dying neurons are found most in the nervous systems? (2 pts) Most often, neuronal death occurs at the time when neurons innervate their target tissue. c) Give two reasons why it may be beneficial for an animal to overproduce neurons during development and then lose them to cell death. (3 pts)
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2) During development, excess numbers of neurons are produced and many of them die through the “intrinsic” apoptotic pathway. a). What is the role of cytochrome c in the death of these neurons? (4 pts) Once released from mitochondria, cytochrome c binds to Apaf1 (apoptotic protease-activating factor 1), which results in formation of the Apaf1-caspase 9 apoptosome complex and activation of the caspase 9 . b). What is the role of caspase-9 and the caspase-3 in the death of these neurons? (3 pts) Caspase-9 is a specific protease that activates caspase-3. Caspase-3 is a broad protease. Activated Caspase-3 degrades numerous protein species and causes the cell death. c). To find out the function of a protein known as Bax, a researcher generated a gene knockout mouse line, in which the Bax gene was deleted from the mouse genome. This researcher examined the retina of mutant mice and found that there were much more ganglion cells in mutant mice than in the wildtype mice. Explain why? (3 pts) Bax is a pro-apoptotic protein. Knockout of Bax prevents release of cytochrome C from mitochondria; therefore prevent neurons from dying by apoptosis.
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3) (2 pts each) a) The gastrulation process generates three primary germ layers of the embryo, which layer gives rise to the nervous system? Ectoderm b) Which kind of cells gives rise to the peripheral nervous system? Neural crest cells c) What is the growth factor that plays the pivotal role in the formation of a proper neural plate? BMPs
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2009 Exam2key - NERVOUS SYSTEM II 080.306 SPRING 2009...

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