Chapter 2 Protein Composition and Structure 4 15 In what pH range is zwitterionic Alanine the predominate structure? A)0-2 D)2-4 B)9-14 E) 2-9 C)8-10 Ans:E Section 2.1 16 Which amino acids contain reactive aliphatic hydroxyl groups? A) serine and methionine D) cysteine and methionine B) serine and threonine E) cysteine and threonine c) methionine and threonine Ans:B Section:2.1 17 Name three amino acids that are positively charged at a neutral pH. A) lys,arg,and his D) lys,arg,and pro B) his,arg,and cys E) arg,glu,and his C)cys,arg,and met Ans:A Section:2.1 18 In the following peptide,which amino acid is the N-terminus? Phe-Ala-Gly-Arg A)Ala B)Phe C)Phe and Arg D)Arg E)None of the above. Ans:B Section:2.2 19 What is the approximate mass of a protein containing 200 amino acids?(Assume there are no other protein modifications.) A)20,000B)11,000C)22,000D)222,000E)None of the above. Ans:C Section:2.2 20 Which individual won a Nobel Prize for his landmark work in sequencing the protein insulin? A)Pauling B)McClintock C)Gilbert D)Maxam E)Sanger Ans:E Section:2.2 21 Why is the peptide bond planar? A) Bulky side chains prevent free rotation around the bond. B) It contains partial double-bond character,preventing rotation. C) Hydrogen bonding between the NH and C=O groups limits movement. D) None of the above E)All of the above. Ans:B Section:2.2 22 The configuration of most a-carbon atoms of amino acids linked in a peptide bond is A)cis.B)circular.C)parallel.D)trans.E)perpendicular. Ans:D Section:2.2 23 What structure(s)did Pauling and Corey predict in 1951? A)a helix B)B sheet C)B turns D)a,b,and c E)a and b Ans:E Section:2.4Chapter 2 Protein Composition and Structure 4 15 In what pH range is zwitterionic Alanine the predominate structure? A) 0–2 D) 2–4 B) 9–14 E) 2–9 C) 8–10 Ans: E Section 2.1 16 Which amino acids contain reactive aliphatic hydroxyl groups? A) serine and methionine D) cysteine and methionine B) serine and threonine E) cysteine and threonine C) methionine and threonine Ans: B Section: 2.1 17 Name three amino acids that are positively charged at a neutral pH. A) lys, arg, and his D) lys, arg, and pro B) his, arg, and cys E) arg, glu, and his C) cys, arg, and met Ans: A Section: 2.1 18 In the following peptide, which amino acid is the N-terminus? Phe-Ala-Gly-Arg A) Ala B) Phe C) Phe and Arg D) Arg E) None of the above. Ans: B Section: 2.2 19 What is the approximate mass of a protein containing 200 amino acids? (Assume there are no other protein modifications.) A) 20,000 B) 11,000 C) 22,000 D) 222,000 E) None of the above. Ans: C Section: 2.2 20 Which individual won a Nobel Prize for his landmark work in sequencing the protein insulin? A) Pauling B) McClintock C) Gilbert D) Maxam E) Sanger Ans: E Section: 2.2 21 Why is the peptide bond planar? A) Bulky side chains prevent free rotation around the bond. B) It contains partial double-bond character, preventing rotation. C) Hydrogen bonding between the NH and C=O groups limits movement. D) None of the above. E) All of the above. Ans: B Section: 2.2 22 The configuration of most α-carbon atoms of amino acids linked in a peptide bond is A) cis. B) circular. C) parallel. D) trans. E) perpendicular. Ans: D Section: 2.2 23 What structure(s) did Pauling and Corey predict in 1951? A) α helix B) β sheet C) β turns D) a, b, and c E) a and b Ans: E Section: 2.4