BIS102 Hilt F05 FINAL

BIS102 Hilt F05 FINAL - 10f4 Biological Sciences 102 Name %...

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Unformatted text preview: 10f4 Biological Sciences 102 Name % Fall, 2005 _ Last First K. Hilt Final Exam Score (200): pH = pKa + log {[base]/[acid]} Ka = x2/y-x Kb = x2/y-x pH = (pKal + pKa2)/2 Vo = {Vmax / + PKa’s of the side chain R-groups are: D (3.9), E (4.2), H (6.0), C (8.3), Y (10.1), K (10.5), and R (12.5). The pKa’s of the a—COOH and a-NH3+ groups of amino acids are 2.10 and 9.60, respectively. The pKa’s of the N— and C-termini of an oligopeptide are 7.40 and 3.60, respectively. Multiple Choice section. (70 points). Each question is worth 7 points. Circle the letter of the best answer. 1. A pentapeptide contains five different amino acids. Amino acid analysis could give: a) six difi‘erent peaks b) five different peaks Q —- N‘- b" E ’ V c) four different peaks 3’ 8, b E V M "1+ d) a and b E D I I 1 e b and c + t. 4 a, b, and c Nth-4* U04 2. A student has an enzyme that catalyzes the reaction: A + NAD+ H B + NADH + H+ . The student is assaying the enzyme beginning with B + NADH + H“ and needs to keep the reaction at a constant pH of 7.7. The student should use: + ‘ . n a L, ‘ ‘ a) 10 mM phosphate bufi‘er, pH 7.7 H M‘ AAS‘WW‘MA" ‘ u n b) 10 mM Tris buffer, pH 7.7 WW « 1M3“— res «vow r), c. at c 20 mM phosphate buffer, pH 7.7 «W '7-7 . a 0 mM Tris buffer, pH 7.7 Note: the pKa’s of phosphate are 2.1, 7.2, and 12.3. Tris has a single pK3| of 8.2. 3. The final pH (to the nearest 0.1) after mixing 0.10 mol H2PO4' with 0.20 mol of HPO4'2, in a total volume of 400 ml, is: ‘3“ .. ’7-2- - “J - “3'04 fl——— Hyeoq‘ ?——- 390.:- ?—- 90.3 @H 7.5 T '\ b; PE o.l m-QAOD "L 0.2. pat/“m “1 c p . a" e) pH2.4 f*— f 0} a: f) none of the above = 7.2. + 0.30 - 7.5' 4. An essential fatty acid for animals is: a) oleic acid b) stearic acid c) palmitic acid @a-linolenic acid e) phosphatidylserine 20f4 BIS 102 Name Q‘ Multiple Choice (cont) 5. You are purifying enzyme Z. You think that the preparation is not pure, based on the following data: 10. fl) *- pproximately 217,000 rnin'1 a) there is only one band on a native PAGE gel there are two bands on an lEF gel c there are three bands on an SDS PAGE gel d) a and b e) a and c t) bandc A Michaelis-Menten enzyme is assayed at a substrate concentration that equals the K“. The velocity measured is 20 umoles S —>P/min. 12 ug of enzyme was present in the reaction. The molecular weight of the enzyme is 65,000. The turnover number of this enzyme must be: ‘” v.13“ [5 ’5 ¢ ' ) approximately 108,500 min"1 ‘1 1 40 M 5 a f Ind”. 0) approximately 40,000 min'l M 5' /‘ _; ~L IO d) approximately3.7x109min'l 7'" "7"} ‘= ‘2‘” 5 ‘:;w 9IW£= 133:" 6) none of the above “5'9 ¢ A“; I I0 "‘42 TN -— “a — 5 3' ' ' ’ 1.2% s 10'” mo. - 2.:57 no m‘J‘ An enzyme catalyzed reaction yields a Km/ < Km and a Vmax / < Vmax. The inhibitor most likely is a(an): a) noncompetitive I b) competitive I c) irreversible I @ uncompetitive I 6) either a or c In the Sanger reaction, an N-tenninal arginine can be distinguished from an internal arginine because: 6) the internal arginine will not be yellow b) the N-terminal arginine will be twice as yellow as the internal arginine c) the N-terminal arginine will extract into the upper ether phase d) a and b e) aandc f) bandc The fluidity of an animal membrane may be decreased by: a) an increase in the concentration of oleic acid in the membrane, relative to palmitic acid b) a decrease in the concentration of cholesterol in the membrane 0) an increase in the concentration of palmitic acid in the membrane, relative to stearic acid d) a and b e) a and c @none of the above In chymotrypsin, the histidine residue in the catalytic triad is: a) a general acid catalyst @D general base catalyst c) a nucleophile d) aandb e) aandc 3of4 BIS 102 Name 3% Fill in the blank section (50 points). Each blank is worth 5 points. 1. We have extensively studied the properties of the twenty amino acid R—groups. Below is a list of different properties. Fill in the one-letter symbol of the R-group(s) that satisfy each condition. Each question may have more than one correct answer. If there is more than one answer, then give all of them. However, do not guess. Points will be subtracted for wrong answers. '1 —| for caCL poi/M? mew-44’ a) this R-group consists of only three reduced carbons P \J c” one. + 3 2"“ +7. b) this R-group absorbs ultraviolet light F u.) H! \‘i M +3 72‘.” A- 2 c) this R—group can act as a general acid catalyst at pH 7 H K c. g: I g +t “(A —=- +3 (1) this R—group can form salt bridges in a protein at pH 7 p E H 9 E K H W —a +5 e 6'” g +I e) this R—group cannot be present, by itself, in an a-helix *3 i) this R-group participates in the H+ portion of the Bohr effect 2 H K 4 I 4- 3 H /- l 2. A 10 residue B-pleated sheet strand would form [+0 (give a number) H-bonds if it was paired with a strand of 10 residues on each side. However, it would form 5' k/Zgive a number) H-bonds if it only had one strand of 10 residues on one side. In contrast, ten residues in an oc-helix would form éH—(give a number) H-bonds, and 10 residues that were involved in a single reverse turn would form I (give a number) H- bOIldS. '\ M) Na. WW True and False section (30 points). Each question is worth 3 points. For each statement below, circle either T or F. T G; 1. The transport of HCO3' across the plasma membrane of a red blood cell requires Na+ ions. T (9 2. The Km and Vmax of an enzyme are both independent of enzyme concentration. T G) 3. Allosteric enzymes are very common in nature. The models used to explain their S-shaped vo vs. [S] curves are called the “sequential” or “concerted” models. T @4. The best protein purification technique is isoelectric focusing. ® F 5. In a protein purification table, each step in the purification should show an increase in enzyme specific activity. T@ 6. The Sanger method of identifying the N-terminal amino acid would work if the ether extraction step was done using 1 M NaOH instead of 1 M HCl. T @7. Dr. Levinthal showed through calculations that proteins fold in a random manner. T CF) 8. An enzyme catalyzed reaction is assayed at 10 uM S. If the enzyme is reassayed at 20 uM S, the recorded initial velocity will be twice as great. T @ 9. One way for a human to adapt to high altitude, in order to deliver more oxygen to his(her) tissues, is to decrease the concentration of BPG in one’s red blood cells. T @10. Proline will not react with Sanger’s reagent. 4 of 4 BIS 102 Name Q3 = Full Calculations: 1. (15 pts.) What is the final pH of a solution obtained by mixing 200 ml of 0.400 M NH3 with 300 ml of 0.100 M HCl? (Kb = 1.8 x 10's) Show all calculations. 0 LD- mJLBCMao M N033: 0,0900 Me [01431 +1 (0.3wLJCO.IW m m1.) = 0.0360 MQ H+ j“ “A H’ “ x ' 0. can: ,MQ 1044+ 7 h -"* ) “DU/“J = "‘w an 3) Q» g «V‘— + 1? Egg—4 K = ,‘ '“f ‘ "—7.: 5355' x10 _ 0' “$1 6 a. 1 ID 1.? no SL—QJY'P 11:3 mas—J4 xv + .. c . 5 9K“ —- ""8“ q z —= 61.75 +- 0.2.7. = mu"! 2' «5} +3 2. (20 pts.) How many moles of H+ are required to change the pH of 200 ml of0. 100 M arginine solution, pH 12.2 to a final pH where the net charge of arginine is +1.80? Show all calculations. Assume that the addition of H+ does not significantly change the volume of the arginine solution. l. (Awakxmtn M M3) = o. ciao-o W n 2.1 W ' 12.: fl 2' “'3 g.“ our? '23-— “? fi—— “.3 H = L3 (“as V1.2. P f' w) \ 70% __.__.w__.l7o QH-z «V». + lab, «7 b“) “seed-c» use. = \25 + 1913, 1'; -—o‘5 = la} 324:. as 0 '5 = lab, 7; A"? *s- % g .3;— ..;sbg_ J'é = 0-33 W M 3' "a (0'13)("02° “We “+3 +w-02.mo&H“’ + (0.81Mer M5" 0" = +5 o. ecu. Met H-+ 4» 0.02.. M a» +— a. on. WA I4“ = 40‘th We 51+ 3. (15 pts.) Calculate the pI of the oligopeptid -L- -R-K-VWof your reasoning and calculations. W I . H, W amaze ¢& '7’ ronCCf<¥f4at~ 2- ‘jt’at‘ls 0‘" W563‘7-‘l "0 “3‘s 3" eikg szyaxod’e, 0"“;“° “9“J'S \2.$ @ Q a}.wa GD G9 9 D H 4, 3,1, “4- 6 Ho 7.\-\ “0 lo.‘ Ho ‘1': H’ a a + 7"“ g+ 23-— g” ‘7“ g+ 7"- g+ z... 2" +- 2 [1' (t 10" K” 18 1431’ 7'" C9 4- 0 a DA:- ...
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This note was uploaded on 10/07/2009 for the course BIS 52192 taught by Professor Enochbaldwin during the Fall '09 term at UC Davis.

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BIS102 Hilt F05 FINAL - 10f4 Biological Sciences 102 Name %...

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