bio 320 exam 1 key - BIO 320 Dr. Bushart Midterm Exam #1...

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BIO 320 Dr. Bushart Print Name :________________________ Midterm Exam #1 10 AM Thursday July 24, 2008 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 specific 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 drawing 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). Short answer (100 points): There are 8 short-answer questions. 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. Comparison of a protein from yeast and Drosophila shows that only 17 of 60 amino acids are identical (a difference of about 70%), yet the two proteins are functionally similar . a. What can you assume about the tertiary structure of these two proteins and why? Since they have similar functions, they likely have similar shapes. The function of proteins is directly related to their 3-D structure (tertiary). b. In analyzing the yeast version of the protein you find the hydrophobic amino acid Leucine at positions 5, 23, 45, 46, 47, and 53. You know that the Drosophila version does not have Leucine at these positions, yet there is a specific assumption you can make about those amino acids in the Drosophila protein. What is that assumption? Explain. The amino acids at these positions are most likely to be the hydrophobic type. While the specific amino acids may not be lysine, because the proteins are of similar shape (due to similar function) the types of amino acids must be similar. 2. Explain one way in which phosphorylation of a protein could lead to its destruction by the proteasome. You should explain what effect the phosphate group has had (this has multiple possibilities) as well as what components the protein will interact with in order to be picked up by the proteasome. Phosphorylation can do a number of things. The phosphate group may alter the overall shape of the protein resulting in exposure of a signal recognized by the E2/E3 complex. The phosphate group may be part of what is recognized by E2/E3. It’s also possible the
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bio 320 exam 1 key - BIO 320 Dr. Bushart Midterm Exam #1...

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