classes_summer07_153A-2ID18_Final_S05_Key

classes_summer07_153A-2ID18_Final_S05_Key - Name : _ ID # :...

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Name : _____________ ________ ID # : _____________________ Signature : _____________________ Chem & Biochem 153A-2 Summer 2005 Final Exam (200 pt, 2hr 50 min) R (gas constant) = 0.008314 kJ/K F (Faraday constant) = 96.48 kJ/V*mol Standard temperature and biochemical standard temperature = 25 C or 298 K 1
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1) Short answers. a) (2 pt) The chirality of an amino acid results from the fact that its α carbon: A) has no net charge. B) is a carboxylic acid. C) is bonded to four different chemical groups . D) is in the L absolute configuration in naturally occurring proteins. E) is symmetric. b) (2 pt) 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: A) a net negative charge. B) a net positive charge. C) no charged groups. D) no net charge. E) positive and negative charges in equal concentration. c) (2 pt) What is the approximate charge difference between glutamic acid and α -ketoglutarate at pH 13? A) 0 B) ½ C) 1 D) E) 2 d) (2 pt) The peptide alanylglutamylglycylalanylleucine has: A) a disulfide bridge. B) five peptide bonds. C) four peptide bonds. D) no free carboxyl group. E) two free amino groups. e) (2 pt) All of the following are considered “weak” interactions in proteins, except: A) hydrogen bonds. B) hydrophobic interactions. C) ionic bonds. D) peptide bonds. E) van der Waals forces. f) (2 pt) In an α helix, the R groups on the amino acid residues: A) alternate between the outside and the inside of the helix. B) are found on the outside of the helix spiral. C) cause only right-handed helices to form. D) generate the main hydrogen bonds that stabilizes the helix. E) stack within the interior of the helix. 2
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1) continued… g) (2 pt) An allosteric interaction between a ligand and a protein is one in which: A) binding of a molecule to a binding site affects binding of additional molecules to the same site. B) binding of a molecule to a binding site affects binding properties of another site on the protein. C) binding of the ligand to the protein is covalent. D) multiple molecules of the same ligand can bind to the same binding site. E) two different ligands can bind to the same binding site. h) (2 pt) In hemoglobin, the transition from T state to R state (low to high affinity) is triggered by: A) Fe 2+ binding. B) heme binding. C) oxygen binding. D) BPG binding. E) CO 2 binding. i) (2 pt) The amino acid substitution of Val for Glu in Hemoglobin S results in aggregation of the protein because of ___________ interactions between molecules. A) covalent B) disulfide C) hydrogen bonding D) hydrophobic E) ionic j) (2 pt) Which one of the following is not among the six internationally accepted classes of enzymes? A) Hydrolases B) Ligases C) Oxidoreductases D) Polymerases E) Transferases k) (4 pt) For each of the pairs below, circle the (conjugate) base. A) RCOOH RCOO B) RNH 2 RNH 3 + C) H 2 PO 4 H 3 PO 4 D) H 2 CO 3 HCO 3 l) (5 pt) What is the pH of a solution of 1 M HCl? Explain/illustrate.
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classes_summer07_153A-2ID18_Final_S05_Key - Name : _ ID # :...

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