EEEQuestionsIIKEY

EEEQuestionsIIKEY - 1) Which of these statements regarding...

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1) Which of these statements regarding neuron anatomy is false? A. Neurons usually have many more dendrites than axons B. Dendrites are long projections that can travel up to a meter away to reach their targets C. Growth cones play an important role in axon path-finding D. The central domain of growth cones is filled with mitochondria, organelles, & microtubules. 2) Which of these are true for axon path-finding? A. Microtubules are added to the lagging edge of the axon growth cone B. Growth cones get simpler when they have to make a choice about where to grow towards C. Signal transducing receptors in filopodia are coupled to second messenger pathways that affect the organization of the cytoskeleton D. Pioneer axons and guidepost cells appear after axons find their targets, but before fasciculation events. 3) Which of these statements is true for contact mediated and soluble signaling mechanisms involved with axon guidance? A. Long range attraction cues require contact with the source tissue for chemoattraction B. Contact mediated repulsion requires a source tissue that secretes a soluble repellent C. Extracellular Matrix (ECM) proteins and components can interact with axons, the substrate, and other proteins due to variable functional domains D. Integrins (receptors for ECM proteins) and CAMs (cell adhesion molecules)are not involved in axon guidance 4) Which of these is true regarding Cell adhesion molecules (CAMs)? A. If two cells express the same homophilic CAM on their surface, the CAM on one cell will act as the receptor for the CAM on the other cell and vice versa B. Homophilic interaction of CAMs is when two different CAM proteins bind each other C. FasciclinII (FasII) is not required for different neurons to group together to form an axon bundle (fasciculate) D. Axons in horizontal and longitudinal tracts express the exact same Cell adhesion Molecules
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5) Which of these statements is false regarding the signaling molecule netrin? A. Netrin is expressed at the ventral midline in spinal cords B. Netrin is a long or short range axon guidance cue C. In K/O mice lacking netrin, commissural axons fail to reach the floorplate of the spinal cord D. In vivo, most of netrin is soluble rather than existing in a gradient attached to the surface of cell membranes 6) Which of these best demonstrates the need for repulsive cues during the process of axon guidance? A. Robo/Slit interactions prevent commissural axons from re-crossing the midline and mutations in the robo gene cause a “roundabout” phenotype where the axon is stuck crossing again and again. B. Netrin is able to act as a bidirectional guidance cue due to receptor expression on axons C. Chemoattraction rostrally helps axons target the brain after crossing the spinal cord midline D. Wnt4 guides axons expressing the frizzled receptor to grow away from the Wnt4 gradient 7) Which of these is false for axon targeting? A. An axon defasciculates in the region of the target due to molecules that help it
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This note was uploaded on 12/13/2011 for the course BIOSCI 93 taught by Professor Staff during the Fall '11 term at UC Irvine.

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EEEQuestionsIIKEY - 1) Which of these statements regarding...

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