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In a Ramachandran diagram, a larger area represents sterically allowed torsion angles of phi and psi that are allowed in _____ rather than in ______ because there is greater opportunity for separation of amino acid side chains

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1. In a Ramachandran diagram, a larger area represents sterically allowed torsion angles of phi
   and psi that are allowed in _____ rather than in ______ because there is greater opportunity for separation of amino acid side chains.
   
   A) secondary structure...tertiary structure
   B) α helix...β sheet
   C) β sheet...α helix
   D) tertiary structure...secondary structure
   E) none of the above
2. In a protein, the most conformationally restricted amino acid is ______; the least conformationally restricted is ______.
   
   A) Trp, Gly
   B) Met, Cys
   C) Pro, Gly
   D) Ile, Ala
   E) Ala, Pro
3. Which of the following has (have) both a favorable hydrogen bonding pattern and phi and psi values that fall within the allowed Ramachandran conformational regions?
   
   A) alpha helix
   B) collagen helix
   C) beta sheet
   D) all of the above
   E) none of the above
4. * Which of these characteristics does not describe the B sheet?
   
   A) Amino acid side chains are located both above and below the sheet.
   B) B sheets have a pleated edge-on appearance.
   C) They can exist in either parallel or antiparallel configurations.
   D) The sheets contain as few as two and as many as 22 polypeptide chains.
   E) Parallel B sheets containing fewer than five chains are the most common.
5. Which statement below does not describe fibrous proteins?
   
   A) Domains have a globular fold.
   B) These proteins usually contain only one type of secondary structure.
   C) These proteins usually exhibit structural or protective characteristics.
   D) These proteins have usually elongated hydrophilic surfaces.
   E) These proteins are usually insoluble in water.
6. Which of the following changes would not alter the functional characteristics of α keratin?
   
   A) Increasing the number of residues per turn to 4.1 while maintaining the same amino acid sequence.
   
   B) Substitution of a hydrophilic amino acid for a hydrophobic amino acid at position a and d of the 7-residue pseudorepeat.
   
   C) Decreasing the number of cysteine amino acids within each protofilament.
   
   D) Changing the environment surrounding the protein to one that is more reductive.
   
   E) All of the above would alter the functional characteristics of keratin.
7. Which of the following statements is true regarding collagen?
   
   A) The inability to hydroxylate proline results in the inability to synthesize collagen.
   
   B) The α helical structure is ideal for intertwining 3 filaments.
   
   C) Hydrogen bonds between the ?OH groups of Hyp residues stabilize the helix.
   
   D) The requirement for glycine every 3rd amino acid is essential for the triplet helix formation.
   
   E) On average, there is one proline for every hydroxyproline.
8. Which of the following gives the best example of a nonrepetitive structure in a protein?
   
   A) a random sequence of 12 amino acids with high Pα values forming an α helix
   B) an amino acid sequence with the following pattern "...a-b-c-d-e-a-b-c-d-a-b-c-d..."
   C) a 13 residue α helix with a Gln at position n+12 which hydrogen bonds to a residue at position n+10
   D) All of the above statements describe nonrepetitive protein structures.
   E) None of the above describe nonrepetitive protein structures.
9. Which of the following is true regarding crystalline proteins?
   
   A) Many crystallized enzyme proteins remain catalytically active.
   
   B) The diffractive pattern observed during X-ray exposure to the crystal can be used to calculate the electron density map of the crystalline protein.
   
   C) The larger region indicating electron density with in the electron density map, the more accurate the structure determination.
   D) A and B are true.
   E) A, B, and C are true.
10. In the absence of ascorbic acid, prolyl oxidase is unable to oxidize proline residues in collagen to hydroxyproline, resulting in:
    
    A) lathyrism
    B) prion diseases
    C) amyloid formation
    D) scurvy
    E) allysine