midterm_2_002_key

midterm_2_002_key - CHEM 237 Midterm 2 Tuesday November...

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CHEM 237 Midterm 2 Tuesday November 9 th , 2010 Name: ID: Instructions: Copy your version number into the test master box on the scantron, this is version 002 Fill in your ID number in the boxes on the scantron There are 9 pages including this cover sheet and 34 questions on this exam. Make sure you have a complete test booklet. You have 50 minutes to complete this exam. That includes copying your answers on to the scantron form. Useful Information: ° = ±²³´ [ µ ] ¶² + [ · ] ¸ = 1 + [ ¹ ] ¶º E=mc 2
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Name: Page 2 of 9 1. What is true about methemoglobin? A. this form of Hb has a particularly high affinity for O 2 and does not release bound O 2 in the body. B. methemoglobin can be the result of any one of a number of mutations that result in the oxidation of the heme iron. C. methemoglobin has methionine binding to the Fe 2+ instead of His. D. methemoglobin is a result of a single, specific mutation in the α 1 β 2-interface that results in oxidation of the iron to Fe 3+ . E. None of the above 2. The sickle cell mutant, HbS causes physiological problems because A. the R-state forms fibrils that disrupt the red blood cell. B. the R- state dissociates into αβ dimers and loses all cooperativity. C. the “S” in HbS stands for “synthetic”; this variant was actually synthesized in the lab for research purposes and actually has no physiological effect. D. the T-state forms long fibers which disrupt the red blood cell membrane at lower pH. E. None of the above 3. Which of the following substitutions would you expect to disrupt the 3D structure of a protein the most? A. Lys Arg in a buried network of H bonds B. Ala Val in the hydrophobic core C. Glu Arg on the solvent exposed surface D. Gln Asn on the surface E. Thr Pro in an alpha helix 4. Which of the following statements is true? A. Some proteins requires chaperones like groEl and gro ES to fold properly. B. Protein folding causes the entropy of both the protein and the solvent to decrease C. Once a disulfide bond forms it cannot break and reform during protein folding D. Hydrophobic collapse is usually the last step in protein folding. E. Once a protein has been denatured it can never refold. 5. Which of the following statements regarding quaternary structures of proteins is correct? A. Quaternary structure is stabilized by hydrogen bonds between backbone carbonyl oxygens and amide hydrogens. B. Quaternary structure fully describes the folded conformation of a single polypeptide chain. C. Quaternary structure is stabilized exclusively by hydrophobic interactions between polar side chains. D. Quaternary structure is determined solely by the interactions between secondary structure elements. E.
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midterm_2_002_key - CHEM 237 Midterm 2 Tuesday November...

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