Practice Exam 1 Answers Spr15

Practice Exam 1 Answers Spr15 - has-user the Name CHM 3218...

Info icon This preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 4
Image of page 5

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 6
Image of page 7

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 8
Image of page 9

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 10
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: has-user. the: Name CHM 3218 t' 5305 Spring 2015 Pralice Examination #1 Unlverflty 41' Florida Honor Code Statement: "On my honor. l' have neither given nor received unauthorized aid in doing this assignment. " Student signature lull-actions: You would have 2. hours to complete this exam. All books. notes. cell phones. translators and other aids would be prohibited. with the exception of molecular models and calculators. No shanks quodels or calculators. Be sure to budget your time and answer questions briefly but completely. To receive partial credit for incorrect answers, be sure to show your work, particularly in problems involving calculations. Write your name on each page. 1. Amino acid properties. (Total 28 points). a. Draw the complete structure ofa symmetrical dimer made from two copies ofthe amino acid whose I letter code is K. The dimer is formed by connecting the o-amino group of one building block to the o-carboxyl group of the second building block so that a six-membered ring results. All chiral centers should have the (Hystereochemistry and the predominmt ionization state at pH 7.0 should be shown. (Ii points). I). Are the two amino acids in your answer to part a D- or L-amino acids? Briefly explain your answer. (4 polite). G cote, Q-qmww OLA-B H ”“3 5“,,“ (1- ”H; i) “‘ “ G) L 5'6 H u. k on Ha ms“ ‘ ‘- ‘H “ no u Etc-1a» i-l “ ?'°5LL‘H.V“ no, (it Page] new 1"- Name C. Are the amides in the structure described in part a stable when the compound is dissolved in water? Does hydrolysis now: at significant rates in pure water? Briefly explain your newer. (6 points). DJ. . an unfit-.5 on. hug- me b‘fifllfl‘“ “1.1” um iii“; an goth..- on} who! :59 “Mow-yaw On m aha-u “"13- “M. or: ‘mhbh111 shah. wk'hn hflc'hecs 0? ca, 1 ‘lew’r tn Hm. absent; at o LEN-o‘g'flv t?“ wear...) :1. To determine amino acid composition, the omnpound described in port a was hydrolyzed under the Wet: conditions. then the pH was adjusted to 9.0 and an excess of plmylisothiocpnate (shown below) was added. Draw the ptoducfls} that would form under these conditions and use curved allows to show how the reaction proceeds. (3 points). ”at: w 07. 9h ’ ’ 5 P'flmu {J phmylloflliooylnlu ah 9‘4““) u ‘t-i (.0? Q . -O"“' |{ (a H N C “LI 1» Pa " .. We?" of a «J5 9»: Y’s I ‘ 9 ’ “G we 1’ o9 -A . N ‘0‘ . 1. H C NH H I: . ’ 1 ‘ - 3 -"" ....-L H 'WZ- ' H i Web '3 j | k \ r49 .Lmhon on ha. Q-QMTV'IO Snug? ant-1:160, 1-, ?mbo~1monh\l enruyonuhh (and hurl-Sow finn-flub\m?“"5it—]- Luau-ml Kev Nun: e. Drawthcpmducttsnhatwouldbeobuimd iflheneaclion inpandwerecaniedoutupl-I 11. Briefly explain why the mults would be It: sam: at differmt hum the reaction with PI'IC at pH 9.0 (4 points). as cue 1» 9M H, bah. M‘ ‘31- «Mb E- nun-mo run? 5 woo“ ‘0'. *vaammanu) wam‘H-o W13 Waco-at. mmggw‘qlg ‘ h- bwwuhvt. Hu‘fiffl‘ “I: ”t“! ?\.TC. Col-m: on bohn CHIN—25‘ Pages __h»_~wLV-€‘I___ Name 2. This problem explores the effect of chme on pit. values and buffer behavior. (Tom 28 palate). :1. 0f the four diacids shown below1 which would you expect to have the lowest pK. value? Briefly explain your answer using words and chemical shuctures. (4 palms). ”033‘003H HOICVOOZH HOzCNCO 1” I'KHCWOOII" our-lie eeld mum leld undue new Mlle add 0 G) (.0 O 3 o o" o 0‘5 film-lg q... $10 0“ no “he“ 13—d— “EJ + an vko“ W W tau. Wu, h.“ {Mn-uni; 0"- Barnum.“ "9‘“"W" swab- lean mine.“ the»? Beep-tau. (avid-Habit. Vovur- Buns, ca If": many err-ruin show 1.0:an LWL'J' ‘73.: mar-s have art-I'M nub wow) have. 1m. 1::qu 9"». b. The first pK. value for compomds shown in pm a are 4.34, 1.23, 4.19 and 2.83 (not in order). March the pk. 1value In line corresponding diacid. (1 point each}. Oxalic acid ‘ 1-3 Malmic add a.“ Suec'mic acid “HQ Glutaric acid “1-23 c. honeufthe dimidsshown in part3. IhepK. valuesare 2.33 and 5.69. Since both pK. values refer to the same type of functional group, why do they differ? (4 points). on“ M Cusi- gubfis“ m5 ion deb. hm. Hakeem. M5 0. in!) “wank“ Ho km a BOJHN on ~ i-tell . L.“ a": Man mane {Nolan puh in q ”why elvh‘hom" rinsed-we. thwot. urn-nu. a hsku‘odihwa. WT.“ «Lfius'k‘a hug-ow “mam is“ value.) lo wile-wu- 3L?vo\'ofla\ton"r.b,. u “’9?" pl“; Run-Mil 1“"! Name d. Is the dincid desaibad in part c an effective buffer at pH 7.0? Briefly explain m answer. (4 points). NO Tm bum»: var-nah 9w a. wash up} n C...“ 9“.."1- Lo 9&*\. \n he Lou, .} flux} hr. a. Son} Hume: ‘ofl-wm p“ 1.33 an) 3.33 (in-V1} “1.59—ngpfi 1‘0 0 «Yuk; bum wan-maid e. At pH 6.0. if the total comma-anion of the diacid described in part c is 75 amid, what is the mommionofthe form with amt dm'ge of-l? (6 points). O ? 2353 Q Q 53% O o HOJ‘H’Kou =‘- 90%“ . n9 =°°“H“*o° . He 0 .. 1, — z 5] H; =2 5' . HQ a-m mend E3 Lm- ~o"““’““ = hm T ' hm. . u. [nu-.1, - [HILL-[NI [an 1» [Hulwohn ? i '- 1H“): [truth-[H193 EMU wom'm’) ‘ 1““? (madam . “m" w '- PM ‘ “'5 W but know 4"" R c . {\Hh\;-[HL1} ‘ '22-‘2— P 'PI g " ‘93 {uh} I . IO “6 O) 45 6%)) man-9“.) : (tan, -[filk‘|} ‘ 2-5.1 m3 [and f. IfIJOmLofl Ml-lCliaIddedtoZSOmLofthc solution dcscribedinpane.whalislhe final pH value? (6 paints). “phat-£145.35 wee. 7."?! two-I91 u; \ T‘ _—_- ‘zwmé [pi—2;.“ II. ‘_I% I‘DI,M'L .OtIQu-l. y ‘600 mwfii mom efi ‘4' aha lull-0|" U ‘ "‘0‘ _ _} —_ 3 1, - dlb u " 5W0wd- ' n. 1° ' to M 1; moh --t "“‘_.l:.. ‘7-"°“"_ ”JG-Io «an... '- two“ I "300 «Inf-‘9‘ «755%; "Mu 0‘ H’ mwh k' +0 Ha. ha . H” “1—H“ Pages 9‘“! “Li Inbh\"‘om. 9-K has”... G |‘ Iib'aumus “A * Lao .. “3'3 now- uh ‘ Twine" «95 Wit mob. N - we r nod-nam- 1.35- Io’mm ‘ 14?. Holman. 153; bun (1J1H'Dlt) «w.» 4""? PH " fl... Flas< [pm 5 $1] Angular. Kg Nun: 3. Fill in the missing Maturation in the table. You should draw the: predominant species at pH 7. paying cumin. Io “crucial-m. Show canflgumflm Qfafl minim! centers explicitly by dmm‘ug all four attached am. (2 points each; Total 14 points). One or Three-lam- Code and (R) I (5) Muslim hmbuag the] Name 4. Oxytocin is a peptide hormone that plays a very important role in childbirth. II has the amino acid sequence Cya-Tyr-lle-Gln—Asn-Cya-Pm-Leu-Gly. (Total 13 points). 1. Draw the complete mature oflhe peptide as it would exist as pH 7.0. You may neglect smoochemistry in this drawing. {8 point). 0 I" g. e 0“ un‘ 0..fo 11““): . . m" 0 51.1 CH3 6 0 ~22 O H “an “”45 CH1 Lulu 'kqud-JQKN If" .4. 0:: T *1 o L H o ’5 3n Lu 3 NH... CH3 b. him.meside-chajnsof(.‘ys l and Cyséaleoovalemlyjoined. Showthisbondinyow structure drawn above and briefly explain how this covalent bond might affect the strucmral bd‘liwior of oxymcin. (4 points}. '~-‘ ," 't H a '5':- d 3” T NH 5 “ ‘5 ’J‘WO l w Because. hm» ‘hu Ha. Mao ink,“ at H... u“‘“‘ “3"“,5‘“ “' “‘1“ Mosh- “a ”.9th matuwmuhah W"- “:83- hast-:33 in: Name 5. Using the following information. deduce the sequence of the original octapeptide. Be sure to consult the list of peptide cleavage reagents on the last page of the exam. Note that amino acids are listed in alphabetical order in the data. and no sequence order is implied. {8 points). Total acid hydrolysis: Arg. Asp. Leu (2.0 equivalents). Lys. Met. Ser. 1111' ArgC: 2 different products. Each was isolated and hydrolyzed with acid and theiratnino acid compositions weredetermined: #1 (Avg. Leu (2.0 equivalents»: #2 (Asp. Lys. Met. Set. Thr). LysC: No reaction Cyanogen bromide: 2 different products. Each was isolated and hydrolyzed with acid and their amino acid compositions were determined: #1 (Arg. Asp. Leu (2.0 equivalents). Met. 111:); #2 (Lye. Set). Chymotrypsin: 3 different products. Each was isolated and hydrolyzed with acid and their amino acid compositions were determined: it] (Lye. Met. See. 111th” (A13. Asp. Leu); #3 {Leo}. AspN: No reaction taflflc‘r‘w 22.21211. —- 95:. Mr. “(wk/M 7425*375 kits Qt fine). up. A». I) urn-twat bl. Lu... m.h,3 i *1 ”W"- ceam. crown C‘I-wmmen «and 54-min l.“ (1.1 Mg .mbk‘o“ "1‘9“: Heady up may. '0!- C'lr-uMw-Ibl '13:.“ CINE? . *1 fi¢9_\_m.m. “£31.“.Ml- :) "10)th ______———&L I" 2- Haflhw 5'? mafi- ht- Sly-Ls” k5?” -.~Quphh‘ 3...”. it)? a q ?r93ud. Ha- lNJL Oevgoclnov- mm “HQ" it. Mvjt Vie-UL burn A,“ w‘l “A. gr'fiS't'IIb-t W?h}t l-‘tfioolyns to Mp 013..ch ottw may“? Page 8 has—see. 'Il-E‘r Name 6. This problem outsider: n-helices. (Total 10 points}. a. Consider a segment of polypeptide capable of folding into an o-helitt. Will it be thennodynamically more likely to do so if the segment is exposed completely to the aqueous surroundings or completely buried in the non-polar interior of a protein. Carefully explain your answer. (4 polnla). g“, ~55 m o tmfi (n 9 hub“. |V'|\FU;‘¢. T-"Lum e. hg‘bvergn— beat-n5 ram» 9% aim. “at. H Jam-ht «a mu I-M'l‘m on. as shuns m 9.: 4- uo nth-u an “I- “Cake shah. ‘rfib hjhvefhikm gaudy: renal}. Ha- hulk 5° H... 3"hbd‘1o‘to— I. Cut ?¢D‘un Cd‘hufib. ‘1'!” ("m3 H‘ bflz’owdalt 5.3g.unmws M“! 5!- mcfnakoeb Com weAuI on ham, em. on M51. winter 9? o ?fo\-1;ph b. The stability of an o-helix is determined no only by the fonnation of mutpeptide hydrogen bonds. but also by the nature of the amino acid side-chains. Predict which of the following amino acid bomopolymers will form stable u-helioes and explain why or why not in each case. (2 point: eleh). Phlylalcine (Lat). ItpH7.0 - no h'iu- “’1‘: no 15 branch. no 9-week...» Polythreonine (ThrLatpH 7.0 - no his-L unac‘u Lot): B-bmm_ mama-luau :1: mt Polyalglmne' ' (NthflPHB * ot- ?“ n. amt-mom: have no uncut?- [pig £1235), an no thereof-www- «ILotittrtcimt-i no fi—vghmms 0" t" can avian-ii» Pages! Lama: 12‘! Name Amino Acid pK. values "'30 F‘nl IIK-J PKIJ Alanine 2.34 9.69 Arginine 2.17 9.04 12.48 Aapatagine 2.02 8.80 Aspartale 1.88 9.60 3.65 Cysteine 1.96 10.23 3.18 Glutamate 2.19 9.67 4.25 Glutamine 2.17 9.13 Glycine 2.34 9.60 Hislidil'le 1.82 9.17 6.00 lsoleucine 2.36 9.68 Leucine 2.36 9.60 Lysine 2.18 8.95 10.53 Methionine 2.28 9.21 Phenylalanine 1.83 9.13 Praline 1.99 10.96 Sen'ne 2.21 9.15 Wennine 2.11 9.62 Tryptophan 2.33 9.39 Tyrosine 2.20 9.1! 10.07 Valine 232 9.62 Reagents for peptide cleavage ArgC: Cleaves after Mg AapN: Cleaves before Asp Carboxypeptidase: Liberates the C-terminal amino acid 115100.; as this residue is 1101 Pro. If the C-tenninal residue is Pm. there is no reaction Chymou-ypsin: Cleaves after L00. Phe. Trp,1‘yr CNBr: Cleaves after Met LysC: Cleaves after Lyn Staphylococcus names V8: Cleaves after Asp. Glu Themnlysin: Cleaves hefune most hydrophobic residues qus'm: Cleaves after Lys, Ar; Pagelo ...
View Full Document

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern