430exam1_spring_2007_key

430exam1_spring_2007_key - dr. Hogan_S2007_exam1 Q1. What...

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dr. Hogan_S2007_exam1 Q1. What gives proteins such a dominant role in biochemistry? ALL MC = 2PTS EACH 1. the variation in sizes based on number of amino acids 2. the ability to act as a “blueprint” for life 3. their ability to self replicate 4. their ability to spontaneously fold into complex 3-D structures 5. all of the above. Q2. Reversible chemical interactions are mediated by: 1. electrostatic interactions 2. hydrogen bonds 3. van der Waals interactions 4. all of the above 5. none of the above Q3. The energies for hydrogen bonds are approximately (1 cal = 4.184 J) 1. ~ 10-20 kcal/mol 2. ~25-60 kcal/mol 3. ~0.5-2 kcal/mol 4. ~200 kJ/mol 5. none of the above. Q4. What properties of water are important for biochemical interactions? 1. the polarity of water 2. the density of water 3. the cohesive nature of liquid water 4. one and three 5. one, two and three Q5. Key properties of proteins include 1. a wide range of chemical functional groups 2. an ability to possess either rigid or flexible structures as dictated by functional requirements 3. the ability to interact with other biomolecules 4. one and two 5. answers one, two, and three Q6. Why is the peptide bond planar? 1. bulky side chains prevent free rotation around the bond 2. it is an amide bond composed to two different resonance structures 3. hydrogen bonding between the NH and C=O groups limits rotation 4. none of the above 5. all of the above Q7. Which statement(s) below characterizes the nature of how proteins “find” the correct conformation? 1. cooperative folding between components of the peptide backbone and R-groups 2. Progressive stabilization of discrete but transient intermediates along the folding pathway 3. random interactions between R-groups and the peptide backbone 4. answers one, two and three 5. only answers one and two 1
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dr. Hogan_S2007_exam1 Q8. Of the 20 standard amino acids, only ___________ is not optically active. The reason is that its side chain ___________. 1. alanine; is a simple methyl group 2. glycine; is a hydrogen atom 3. glycine; is unbranched 4. lysine; contains only nitrogen 5. proline; forms a covalent bond with the amino group Q9. Amino acids are often referred to as weak polyprotic acids because they can function as either a(n): 1. acid or a base depending on pH. 2. Donate protons in a stepwise manner . 3. polar or a nonpolar molecule. 4. transparent or a light-absorbing compound. 5. Answers one and two Q10. For amino acids with neutral R groups, at any pH below the pI of the amino acid, the population of amino acids in solution will have: 1. a net negative charge. 2. a net positive charge. 3. no charged groups. 4. no net charge. 5. positive and negative charges in equal concentration. Q11.
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This note was uploaded on 03/19/2008 for the course CHEM 430 taught by Professor Redinbo during the Fall '07 term at UNC.

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430exam1_spring_2007_key - dr. Hogan_S2007_exam1 Q1. What...

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