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MT2 W11 section001

MT2 W11 section001 - NAME_ MIDTERM 2 – WINTER 2011...

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Unformatted text preview: NAME:__________________________________________________________________________________________ MIDTERM 2 – WINTER 2011 SECTION 001 READ EACH QUESTION CAREFULLY. PICK THE BEST POSSIBLE ANSWER Gas Constant: 8.314 J/mol.K or 1.98 x 10 ­3 kcal/mol.K 1) Alpha Keratin can be composed of all of the following EXCEPT: (5 pts) a) Filament b) Coiled coil c) Protofibrils d) Fibroin e) Central Rod domain 2) Which of the following thermodynamic terms determines whether a reaction occurs spontaneously? (5 pts) a) ΔG# b) ΔGo c) ΔH d) ΔS e) ΔG 3) The enzyme Lacrymatory factor synthase uses which of the following as its substrate: (5 pts) a) allinase b) Prensco c) Thiosulphinate Substrate = propenyl sulphenic acid d) Propanethial S-oxide e) None of the above 4) At low [S], when [S] is very much less than Km, the rate is directly proportional to [S]. The rate of this reaction is said to be: (10 pts) a) zero order b) first order c) second order d) proportional to [E]t e) dependent on Km/Vmax 5) The central rod domain of a keratin protein is approximately 95 residues in length. The length of this keratin domain in Angstroms is: (10 pts) a) 46.8 b) 134.6 c) 13.5 .51nM/turn X 1 turn/3.6AA X 95 AA = 13.46 nM = 134.6 Ao d) 47.0 e) 95.0 6) In parallel B ­pleated sheets, adjacent chains orient themselves: (5 pts) a) behind each other b) in the same direction c) in the opposite direction d) in no particular direction e) adjacent to an alpha helix 7) The assembly of multiple subunits within a protein is called its: (5 pts) a) planar structure b) primary structure c) secondary structure d) tertiary structure e) quarternary structure 8) In the reciprocal plot for pure non competitive inhibition, one of the terms below changes by (1 +[I]/Ki) when compared with the case for no inhibitor. Which one changes as a function of the above term? (10 pts) a) -1/Km Km is same, Et doesn’t matter, Ki’ not for pure NC. Slope changes b) [E]t c) Km/Vmax d) Ki’ e) All of the above Consider the Michaelis Menten kinetic data present below and answer each of the following questions ( 9  ­ 13) Vmax (mmol/ml.min) (or Vmax app) Km (or Kmapp) (mM) No Inhibitor 35.0 5.0 [I]1 = 10 mM 20.0 12.0 [I]2 = 10 mM 35.6 10.0 [E]t = 10 ­6 M 9) What type of inhibition is exhibited by Inhibitor #1? (10 pts) a) competitive b) non-competitive c) mixed d) uncompetitive e) double displacement 10 ) What type of inhibition is exhibited by Inhibitor #2? (10 pts) a) competitive b) non-competitive c) mixed d) uncompetitive e) ping-pong 11) What is the Ki for Inhibitor #2? (15 pts) a) 5 mM b) 10 mM c) 10 µM Kmap = Km (1 + [I]/Ki) d) 20 mM e) 1.0 mM 12) In the absence of inhibitor, under conditions of initial velocity, and at saturating substrate concentrations, what is the turnover number for this system? a) 3.5 x 107/min b) 3.5 x 107/sec k2 = Vmax/[E]t = kcat 5 c) 5.8 x 10 /min d) 1.0 x 10-6/sec e) 7.0 x 106/min 13) What is k2 for this system as described in problem #12 above? (10 pts) a) 1 x 107/min b) 3.5 x 107/sec same answer, but convert to seconds c) 5.8 x 105/sec d) 1.0 x 10-6/sec e) 7.0 x 106/min 14) The standard state free energy of hydrolysis of ATP is  ­30.5 kJ/mol ATP + H2O  ­ ­ ADP + Pi In mammalian blood cells, the concentrations of ATP, ADP and Pi are 2.25, 0.25, and 1.65 mM, respectively. For simplicity, consider this reaction to take place at a pH of 7.0 and 25oC. What is the free energy change in kJ/mol for this reaction? (15 pts) a) -4.21 x 10-3 b) + 3.68 x 10-3 ΔG’ = ΔGo’ + RTln[Products]/[reactants] c) -52 d) +42 e) none of the above 15) What is the ΔGo’ in kcal/mol for a reaction when Keq’ is 1.5 x 104 at 25oC? (10 pts) a) -3.2 kcal/mol b) 1.5 kcal/mol c) 10 kcal/mol d) -15 kcal/mol e)  ­5.7 kcal/mol 16) What type of reaction mechanism is shown in the graph below? (10 pts) a) b) c) d) e) pure non-competitive inhibition double displacement bisubstrate mixed non-competitive inhibition random single-displacement bisubstrate ordered single-displacement bisubstrate NOT INHIBITION: two substrates 17) Fatty acids are often described by a “symbol” denoting the number of carbons and double bonds. Which of the following common biological fatty acis is denoted by the symbol “18:1”? (5 pts) a) Linolenic acid b) Myristic acid c) Palmitic acid d) Oleic acid e) Linoleic acid ...
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