BIO 320 2010 Spring Exam 2 Key

BIO 320 2010 Spring Exam 2 Key - BIO 320 Dr Bushart Print...

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BIO 320 Dr. Bushart Print Name:__________Key_________________ Midterm Exam #2 9 AM Monday March 8, 2010 General instructions: Read each question carefully and don’t hesitate to ask if a question seems unclear. Trying to provide an answer for every question is advantageous; you will not be penalized for guesses. The short-answer questions have speciFc answers, although for some, more than one answer is possible. If possible, answer each question in the space provided, but if needed, continue on the back. If you use a diagram as part of your answer, be sure to also include appropriate labeling and/or a short written explanation. To receive full credit you must clearly and fully answer the question being asked. Partial credit may be given in 0.5 point increments. This exam is worth 100 points (the points for each section/question are noted in parentheses). Use pen if you want a chance for a regrade. Short answer (XXXX points): There are X short-answer questions over 3 pages. Write a clear concise answer for each question. Some questions may have more than one possible answer but require you to defend your choice. Be sure you include clear explanations. Make sure your response answers the question being asked! 1. Certain molecules can travel from extracellular spaces to the nucleus in order to alter gene expression. Explain why a molecule like this might need to be handled by two distinct transport systems. (This has to do with equivalency of spaces and can be determined by considering if a membrane has to be crossed or not.) There are two distinct spaces involved in this process. The inside of the nucleus is equivalent to the cytosol, so the molecule would Frst need to get to the cytosol by crossing a membrane (transport system #1) and then transition between the equivalent spaces of the cytosol and nucleus (transport system #2). [System #2 is speciFcally gated transport.] 2. Imagine you have access to inhibitors that will only impact speciFc transport proteins of your choice. Answer either part i or ii, but not both. i. What would you target to prevent a neuron from establishing a Long Term Potentiation (LTP) response while still allowing it to respond normally to pre-synaptic stimili? Explain your choice. There is really only one obvious choice for this situation, and that would be to inhibit the action of the NMDA receptors. This will prevent the in±ux of calcium necessary to initiate the series of events resulting in LTP. ii. What would you target to promote rapid Fring of a neuron in response to a stimulus that is just above threshold? Explain your choice. Here we want to abolish the rate control. To do that you would want to inhibit the early/ rapidly inactivating K+ channels. This would allow the voltage-gated Na+ channels to work as rapidly as the delayed voltage-gated K+ channels can reset the membrane potential.
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2 3. A single-pass transmembrane protein encoded by a nuclear gene requires two signal sequences to reach its destination in the mitochondria. Where would you
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BIO 320 2010 Spring Exam 2 Key - BIO 320 Dr Bushart Print...

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