BIO 320 2010 Spring Exam 3 Key

BIO 320 2010 Spring Exam 3 Key - BIO 320 Dr Bushart Print...

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BIO 320 Dr. Bushart Print Name:__________Key_________________ Midterm Exam #3 Monday April 12, 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: There are 8 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. BiP (Binding Protein) is a soluble ER chaperone protein. a. ( points) Based on what you know about cellular transport, describe the signal sequences that a BiP would have (before any modiFcations). Assume co-translational transport. Explain your choices. Being an ER resident protein BiP would originally need a hydrophobic ER import signal to enter into the ER in the frst place (this would be cleaved oFF aFter import, but should still be mentioned as necessary). To be retained in the ER, it would also need a KDEL sequence For retrieval by KDEL receptors. b. ( points) What affect, if any, would inhibition of H + -ATPases have on the localization of BiP? Explain. This would lead to a leakage oF BiP From the ER and on towards the Golgi and/or plasma membrane. These ATPases acidiFy compartments. Lower pH is used to modulate the activity oF the KDEL receptors by allowing them to bind to KDEL containing proteins so that they may then be transported back to the ER. So without the change in pH the receptors won’t be able to retrieve the BiP. Partial credit For saying it would not have an eFFect because oF kin recognition helping to retain BiP. It would help, but BiP that did escape would not be retrieved. 2. Use what you know about the organization of the cell, and Golgi in particular, to answer the following questions. a.
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BIO 320 2010 Spring Exam 3 Key - BIO 320 Dr Bushart Print...

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