BIS102 Hilt Sp07 FINAL MWF

BIS102 Hilt Sp07 FINAL MWF - 10f3 BIS 102 Name gigs“ ....

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Unformatted text preview: 10f3 BIS 102 Name gigs“ . Spring, 2007 MWF Last F1rst K. Hilt Final Exam Score (200): Equations: pH = pk, + log {[b]/[a]} K, = xz/(y-x) Kb = x2/ (y—x) pH = (pkal + pKa2)/2 (K,)(Kb) = 1 x 10‘14 F = (q1 qz) /e 12 AG = AH — TAS v0 = {vm [S]}/ {Km + [3]} Amino acid pKa’s: a-carboxyl group (2.1), a—amino group (9.6) side chains: D (3.9) E (4.2) H (6.0) C (8.3) Y (10.1) K (10.5) R (12.5) Oligopeptide pKa’s: C-terminal carboxyl group (3.6), N-terminal amino group (7.4) 1. (25 pts.) How many moles of HCl are required to change the pH of 100 m1 of 0.200 M arginine buffer, pH 12, to a final pH of 2.5. Put your answer on this line: 0. 0 3 moles PF . To receive credit, you must show all of your work on the back of this page. 2. (25 pts.) Calculate the net charge of the peptide WDCKHRV to the nearest 0.01 at pH 8. Put your answer on this line: -—- o . 13 . To receive credit, you must show all of your work on the back of this page or the other page. 3. (25 pts.) Enzyme Z catalyzes the reaction: A + NAD+ (——> B + NADH + H“. Imagine that twenty-five I.U.’s of enzyme Z were catalyzing the above reaction, from left to right, for one minute, under Vmax conditions, in a 3.00 ml assay volume. The assay is buffered with 25 mM phosphate buffer, pH 7.70. What will the pH be at the end of that one minute? Recall that the pKa’s of phosphate are 2.1, 7.2, and 12.3. Put your answer on this line: 7. 0 7 . To receive credit, you must show all of your work on the back of this page or the other page. 4. (35 pts.) Calculate the missing values (X) in the following enzyme purification table: - +§ Volume [Protein] Total Activity Specific Fold ead‘ ml m ml I.U./ml I.U. Yield % ' ' Purification 2000 100 X1 1.00 0. Z Fraction 2. resuspended 200 20 12 X2 120 X3 60% (NH4)2so4 2m, 0 llet 3.afi'1nity column 200 400 X; 1. Write your values in the above boxes, right underneath each X. You do M need to show your work. I 20 The rest of this exam is multi le choice. Each question is worth 10 points. Circle the letter of the best answer. 5. The major weak bond involved in holding subunits of a protein to each other is a) van der Waals b) hydrogen bonds hydrophobic effect ) ionic bonds 20f3 BIS 102 Name % 6. Enzymes manage to catalyze reactions by a) decreasing AHt b) increasing AH:t c) decreasing A81 d increasing AS"t @ 66a?) G‘c” 66b3, 66d” g) ¢6a99 “d” 7. Dr. Pauling proposed that enzymes best bind a) S b P the transition state (1) SandP e) I 8. Binding of just one of these allosteric effectors to Hb creates two salt bridges. This allosteric effector is a) BPG b) H* C C02 Cl- e) co 9. A student carries out a series of assays with their enzyme Z. They determine the Km and Vmax. If they now repeat the series of assays, but this time use half as much enzyme Z in each assay, the kinetic results will give a) the same Km and Vmax b) a lower K"n and lower me c) a lower Km, but the same Vmx d a higher Km , but the same Vmax Q the same Km, but a lower Vmax 10. Coulomb’s Law is applicable in biochemistry when discussing a the hydrophobic effect ionic bonds c) hydrogen bonds d) disulfide bonds e) van der Waals interactions 0 all of the above 11. Purification of enzyme Z requires the use of two difi‘erent assays. The two assays are measuring a) protein concentration, and pH b) enzyme Z activity, and pH @ protein concentration, and enzyme Z activity d) protein concentration, and salt concentration 30f3 12. Company A offers 5 ml of trypsin, containing 100 I.U.’s and a specific activity of 44 I.U.lmg, for $100. Company B offers 3 ml of trypsin, containing 300 I.U.’s of trypsin and a specific activity of 40 I.U./mg for the same price. Company C offers 6 ml of trypsin, containing 250 I.U.’s and a specific activity of 33 I.U./mg for the same price. We plan to use the trypsin for sequencing unknown proteins. We should purchase trypsin from: @companyA ______9 NM te- «kl W 9M company B - c) company C d) 46a39 “c” e) “b” or “c” 13. A student needs to maintain the pH of a solution at pH 7.5. The buffer will maintain the pH of an enzyme catalyzed reaction that consumes H+. Which will be the best buffer for the student to use? a) 0.10 M bufier B, pH 7.5, where B has a pKa of 7.7 b) 0.10 M buffer C, pH 7.5, where C has a pKa of 7.3 0.20 M buffer B, pH 7.5, where B has a pKa of 7.7 0.20 M bufi‘er C, pH 7.5, where C has a pKa of 7.3 e) 0.10 M buffer D, pH 7.5, where D has a pKa of 7.5 pH’ is «gain? *0 a» we! Le. 85* are Alsaflwm‘vé. we M a \oerQ—M/ wiH» a. \Maflr r¢9¢VVOir 3“.“4," +5 (a.le HM, unswva \‘w‘. 3‘ 25' 1.14.3 0.0031 9H; 2: QM... * '0‘), ii 770 2. 7.2 +- “155‘; 0.5% I”? 2:. . = 3.15 _ z 3'": u- a .- b Tilb b 6. 7$q (0.7;?)(Z$ M“) IY~77 m” 9 -'~ 6.03 MM Gk Pug: Pm 9 1.39; -' '72 + l J‘sm' $3) ...
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BIS102 Hilt Sp07 FINAL MWF - 10f3 BIS 102 Name gigs“ ....

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