Biol Chem 153 A Spring 2006 Midterm Exam

Biol Chem 153 A Spring 2006 Midterm Exam - Seat # _ Last...

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
Background image of page 1

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

View Full DocumentRight Arrow Icon
Background image of page 2
Background image of page 3

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

View Full DocumentRight Arrow Icon
Background image of page 4
Background image of page 5

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

View Full DocumentRight Arrow Icon
Background image of page 6
Background image of page 7
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Seat # _ Last initial _-__ Chemistry and Biochemistry 153A Winter 2006 Midterm Examination A Print your full name (last name first) Student ID Number _, Print your TA's name Discussion section # [or time & clay] I have read & understood the instructions on this page. I have not used any prohibited materials nor have I given or received any heli while taking this exam. Signature INSTRUCTIONS YOU SHOULD HAVE ONLY YOUR WRITING MATERIALS, ERASER, APPROVED NON- PROGRAMMABLE, NON-GRAPHING CALCULATOR WITHOUT CASE OR COVER AND YOUR PICTURE LD. ZIP EVERYTHING ELSE INSIDE YOUR BACKPACK AND STORE IT ALL THE WAY UNDER YOU CHAIR. NO OTHER ELECTRONIC DEVICES OR CELL PHONES ARE ALLOWED. NO BOOKS OR LOOSE PAPERS OF ANY KIND SHOULD BE IN THE VICINITY OF YOUR DESK. READ EACH QUESTION CAREFULLY! SHOW YOUR CALCULATIONS! WRITE YOUR LAST NAME IN THE SPACE PROVIDED ON EVERY PAGE OF THE EXAM. NO CREDIT WILL BE GIVEN FOR ANYTHINfi WRITTEN ON THE BACK OF A PAQE QR ANYWHERE OTHER THAN THE SPA CE PROVIDED FOR EAQ ;H M ANSWERS MUST BE BRIEF AND TO THE POINT. WHERE A WORD LIMIT IS SPECIFIED, NO CREDIT WILL BE GIVEN FOR THE PART OF THE ANSWER IN EXCESS OF THE LIMIT. Numbers in parentheses represent the point value / i (0 Name _ ' 1 1. (27) a. (5) Although it is negafpyf charged, the deprotonated form of any carboxyl group is stabilized due to [ eswf’m ( ( Thus the pKa‘s of carboxyl groups are often below neutral pH. Acetic acid is a wea‘V carboxylic acid with an approximate pKa of 4.8 at 25°C. The pKa of wne‘s carboxyl group is ) 0W? f“ than that of acetic acid due to the combined l " L’i "‘- L I‘m“ ( 1 and microenvironmental effects of the nearby 0"“ 3 V‘ c : group. b. (22) The four protonation states of phosphoric acidi'phosphate are Show below along with the pKa for each deprotonation. H+ H+ H+ O O O 0 H II - ll - __ u _ Hod-T—OH Ho—T—o HO—li'—O o—Fl’—O OH H+ OH H+ 0. H+ o_ pKa = 2 pKa = 6.4 :. pKa = 13.4 1) (12) Using the concepts of microenvironmental effects, briefly explain the very low pK.I for the first deprotonation and analyze the reported change in pKa for each successive deprotonation of inorganic phosphate. [5 150 words] . 1r) _/ (PrM‘DHRJ'J\ If"- V? f»; /()L./ bfitcwiu 3 Wt {:11} Hr Iv; (0)} I {htre [5 Q ~ rikfli dfiwblt 01'. f w‘iq,'(L Stall-ti. r1(-" ..-....;....-..}..... .-..-.inuri.....i.§-.....;....-.. ..... - fi 1 .-....i-...-.i.......i-..-...§-..-....--..§.-..-+ ' ' . 10 . .i. -.;- .. pH : ..--:....-.L-....i-.....i.-.._.. .-. . .-. .. ' i E a i . - : i i hi.-. uni.-. .-.i...._.l_-..-.!-u—-. - "r i i E a, i a : : : - : : : ' i I I I 2 - —!--.---:u_..-.E-u- -—-i—-----Eu---_.. - “if. E i i a i i ' i i i moles of NaOH .1 f! 2. (34% (1\) ' ich free protein amino acid has two carbon bonds to it a-amino group? b. (1) Which chiral protein amino acid does not have the S configuration around the Cit—carbon? d. (2) If you add OH' to a diiute solution at pH 8.5 containing 100 mM boric acid (HA) (pK,= 9), wh treaction would you expect to initially occur to the most significant degree? XV OH-JHAQHgoiA e. (2) If you add I-I+ to a dilute solution at pH 10 containing 100 mM acetic acid (pKa= 4.8), what reaction would you expect Vto initially occur to the most significant degree? + n- /i/ H l— 0 H ‘9 H z 0 f. (3) The entire 3-dimensional conformation of a polypeptide is determined by rotation around the FL: and £5 3 /k '9 bonds since rotation around the f i "(if bond is restricted. g. (2) The restricted rotation referred to in (f) above gives rise to a planar configuration that includes atoms and is * ’{/ i 1“flirted was a fife it “ic- £_7i°'i - , ‘9 N 1“ h. (11) The sequence of a fragment produced by - stion of an intact syn/peptide protein i ‘ N-ser—glu-asp-ile-va n-his- t-asn-tyr—val-l ys—his-le gly-gly—i - eu-C '5 * @gg@(§gf7%910@ 1314 16.17%” h k - k n + - R k K 1) (1) What is the predominant net charge on this peptid eg ent at physiological pH (~7)? 2) (1) What is the isoelectric point of this fragment? 3) (5) If this segment forms an (it-helix, will it be amphipathic? '95 If so, circle the residues in the seguence shown above that will most probably form the hydrophobic face? You may refer to the figure below to confirm ((6 your answers. 4) (4) What specific weak interactions will provide major stability to the u—helix referred to in (3) above. ":0 r“ w m; {on f \ Bod-Ur Iq (in, Rabi: 7C_’”'A5.(ag“g.1.he_l.mua§.tar@1helix b this --__ icul seuen e? - I I M-IIlC MH“ I ' -' i. (2) The sequence of collagen’s polypeptides is dominated by three amino acid residues, two of which might seem inconsistent with its triple helical structure. However, it turns out that these residues are quite conducive to this particular structure which does not consist of (it—helices, but of helices that have 3.3 residues per turn. Nam these two (ky residues? ii“! & 9‘10"“ j. (2) In what way might two or more fi—pleated sheets associate with each other to pro uce a strong vcifvr "o Land-ting What type of weak interactions would stabilize this association? I" k. (3) For each of the following weak acids, which form 1 HA gr A') would be pr e t at higher concentration at the given pH? par an an 211 - as LH _ (k 9 6 3 M— 2 4 __fi_ 4 4 t l. (2) Ra the interactions of the following amino acids with valine (1: most favorable = most unfavorable) k glutamine J; glycine _L leucine L arginine histidine 1; serine *1? 6/: "*‘xu/ . 3. (19) a. (2) Write the letter of the drawing below that accurately represents the molecular structure of sucrose on this line. A. B. C. CHon CHzOH OH H OH H H H OH CHEOH 0 OH 0 ’t" (H OH H O ‘5, ~ on HOHZC H H H CHZOH . (— If I V e 014 H OH CHZOH OH H , (_ —u H . (6)Wn'te a systematic name for the following compound. C ".=" r a ’ r“ b g HOHZC /l’ CHZOH O W// A196. 7‘1ffinnoie c. (2) What characteristic of glycogen makes it more suitable as a short-term energy storage compound for animals than ,k Mmylopectin would be? 4'1 Mo" "d‘fl I‘M Mi “’73 5N!“ dob“! ‘ ‘- d. (l) Storing glucose polymers increases water uptake by cells as compared to storing glucose monomers. TRUE @ e. (1) A number of proteins are linked to oligosaccharides. GEE FALSE . X \f. (1) In the monosaccharide derivatives known as aiditols (sugar alcohols), the aldehyde group is re 5!’ W the appropriate common name of the sugar alcohol derived from D-glyceraldehyde. g.(6) Compare and contrast the molecular structures of cellulose and glycogen. Include how th mole lar structure leads to ' 5 formed by these molecules. I icate how the the specific macromolecular ' su1t each of these compounds to its function. [5101! we:- “r Wire-m Strum or «may an ‘ r r ' a H l .3 ; '« Mme: K 40 fll‘ffogen Mifltg d— «Mm I. Thu “4* (P “‘9‘” 1‘4‘1‘ ' _._——-——I Fulfill», . {Vt-ah} Hath wit/H £12155. It It (was: one} abut \él7(bcjem ~3 0 (MW OEMEGH“ pflfylarclqoj‘JC / Luz-wk) wan? CQQ;hJ lLVLHLH Mm!" flair/(Ir arr‘ fall-r” FLO Bea/IR AW“. M4” (“‘0”??? “’3 L “(PAFE' Mmtc‘pl lvl flow? , m7 mnhvxo‘l; ladle, fil-A 039-" “91.41,, Pic“ Head 4-7 S‘He’c energ7 man effi't’gHZ/y .wu— (mg fErTUcls ,( 4.,“th 51:- hm, hm (rm! 1' U l 3 Name; 4 4. (25) a. (1) Which of the following is the parent compound for phosphatidylethanolamine? & ’5 phingosine b. glycerol c. ethanolamine (1. phosphate e. phenanthrene b. (4) What are the advantages to animals of storing energy in the form of lipids instead of carbohydrates? 8‘! D 3 a. Lipids have more reducing ends that allow faster breakdown. Lipids are stored anhydrously. c. Lipids are more highly reduced so they can be digested faster. 2 d. More energy can be obtained per unit mass of lipid due to its lower oxidatiep vte. c. (5) Which of the following lipids serve as components of biological merobranesfi’fiK 1' §][Wi-ite the letters of all that apply] A. 1-stearoyl-2—oleioyl-3-lauroyl glycerol B. cholesterol C. cerebroside 2, D. N—myristoyl-sphingophosphocholine 1-glycerate-Z-stearoyl—phosphatidylserine [ d. (2) Which m of the lipids listed in part (c) above do you think has the least hydrophilic character? E A ‘ e. (1) A membrane rich in stearic acid would be more fluid than one rich in oleic acid. TRUE FALS :5 f. (1} Glycerol is the parent compound for cerebrosides. TRUE m 9/ g. (1) The bonds between fatty acids and glycerol in glycerolipids are 0‘ I" C linkages. h. (10)The following cartoon of a cross~section of an imaginary plasma membrane was drawn by a student. You are to evaluate this cartoon and deduct one point from the student’s score for each individual error the student has made in representing a real plasma membrane. (Note that the representation of all kinds of membrane lipids by a single symbol is acceptable.) EXTRA-CELLULAR - . ' O O 3 2) Give a term indicating to which of the two general categories of membrane proteins each of the following belongs: Protein Protein C 1“ “"7” ‘- i ‘ protein D lob-5;: L 3) Protein B belongs to the same general category as protein(s) E Q , and it can be further described by what two additional terms? +F0~n> WM Bram l and ~ 553.4 In“ “"3 l 4) Which of the following would you expect to have the largest percentage of hydrophobic residues at its surface? Protein A You can’t tell (CIRCLE ONE) 5. (20m. (5) 5 Name 5 List five reasons why proteins are better suited to catalyze biological reactions than the chemical catalysts used in general igemlsnilfii'mn W“! °" towel P” (can In: Wrmchl W 16624; 2) Ont-M.“ r. (A ll) UV" “We 41m HEM-L whoa Um ‘22 LA c" 3) da‘vu cam Cpcrc} w ,9 (flue-F MA MI"; 4) Y0“ Um sand W“ A Had tea is so in Bred VH9 Wk?“ “"3” 5) CL‘C‘MMo U (Gu— demem m hing b. (6) Which of the six classes of enzymes would catalyze each eggs: following reactions? H o ’ValL ‘%=9._____._ Y + o=c...—_o CH3 CH3 (.300 COO’ $00 000' CH2 J__ ii” _I r £3.42 + —0 CH + OH C--H 0 K ' Clo r‘t’Clud—m 5e Elma (INS “as; _.. + HO -CIH-COC3 Ito—COO coo Isocitrate Succinate Glyoxylate _ / L10 5 e c. (9) Write a balanced equation for the reaction catalyzed by lactase (systematic name = lactose hydrolase). Use names and Ho 0 (*0 91% “a , 0 0 H + Hz a? a OH 0!! structures for all reactants and products. H' a Ho “0 e H j)” + oh if '0 o H O OH OH Nmne ymoles BLA produced The following data were obtained for the enzyme catalyzed reaction, LAB ——> BLA in the presence of 0.008 pmoles of the [LAB] enzyme, LAB-isomerase. 653) er second— .0397 .Olblfil 28 25 mM 100 mM 67 ,5 if H e m M m a A ... d W In m 2% w k a _ m y. m I 1W Um x .m m r.— k. t I . o It a m , m ... rti n n K m a o .“ II. n... (I .w & a ..T .. M B w / III-II III-uI-II-u III-II ..nul- lulu. . r. nil-u Inn-I.lulu-Inlanuul-AI-IIA... .1 . .u u. .n . m rt? 8 U . . — . A . _ . . l V . . . . 1 , . . . . . P 11 o m . . . . u / .x - - . _ — . . . . . ,4 . , . . . 6 . b .m . . . . . I - u . u u . V .II a P .fulnlIfllllIllnurlull”.IIIIIdIIIJflITIIIIIdIIIIIquIIIIIqIIIIIJIIIIII".III-I M e m . . . . n ,,u n n u u n a .m w" u u u . ,. u . u u . e t ,m a _ . _ _ n u/ .. u _ . n 3 .m w a...u...I.-._-|-.--T....uIT..|-..-.I.--..I/n...t;n..Iunuun:m-|-n.._tu--....1--.|. 0 K .m n . . . - . . / _ , . _ u . m a ..m . . . . . . , n / _ u u . o e u . . . . . u . x _ _ . . ..U n u _. u w m n t m u u m e m .1 hs-unlhunuluuruluun Ian-.- uuuuln ...I: .Inu- nuull-uu-IIIF-I-c- ...-..- S s" u u u .u .. , u u u m .n m m. _ . u u u n ,. u/ . . u e w I u r n u n _ u u u x u m m u m J m m dull:IIHIIIIIIWIIIIIIUIIIII InIIIIIIL—IIIIIIHJIIII dull IJIIIIIIHIIIIIfiIIII: m .nh L f b . _ . - u u h . _ - . _ “J O .l. . u . . . . _ I . u . B t m . . . u u n n u, / . u m m la]. n u n . . . . . u u - M 0 0 ...-IIIIJ- lull-illnulalllIIInIIIIIIu-oIII-“IlglInfill Ila: Illa—Illlllullull f in . h n . . . . . . o q nw a I - m“ u n n u u m u u u w .mw m a . . . n H .r:..Iu...|.h..t...rlu...h....-|+..I..T1....ur.uN%| I . . . i ..L .. n. m. B £5 + t . a . . . . . . . . .nlv t) TH E . . . . . _ . , . l (I . _ . . u u n u . . 4 u H 1': .l e . u u n u . u u . u // u e . an . . . - . t m ...I:.T--.J--..n-".---.."ill".-...IT-.--."--....-.T..icy--14."...n.-- 1-H. a m .m d u u . _ — . u — u u .M y m h e u . u n n n . u . . . a «m. m l P S . . . . . V a e _ . . . u _ . u _ . u I. a . We .m . . . . . . _ . L e . . 4. . 2 .I. . x, I! C ,m u m u o." u m u o. m n." m cm . s m m" n u u u u u n n u u s w kw s 1m...wuulvufi.|:-.un:--ITIII-ITII:.vluu...m:n.tum..I..u-|.--d|....lu.-.ulu 10 KC 0” .m _ u . - . . — . /. m" m u u u u u n u m n /«\O , Mp m” n u . . . - . . u . . . . ., r a O B _ . _ . . _ . . . . ., .\ E . ...1--....|.-.-..-.il....-I-n...t---.T.-.-+...1!..-I..-...I...-1-uu.|r.-.l. . m x l .l . — . . . . . . . I ..u C . . . . _ . . . _ . . v 0 S — . u . . V . . . . . . . _ . . . .. ...l y E w u u u u . . . _ u u . m . K c r w ....1-...-....-.... ...-.l. .-1.-.“.-.--."....-- .--.-.-...-...T-..- .-.-.- K B m d . __ J a ._ ... . c . . - 1. . B . . . . _ . . n pl? I. t. n u u . . . . . . . . C C C ..I. . . . . . h u 1: :l e _ . a . - . _ . I. f L . . . . . . . . . e 11 f p . u . . _ . . _ n . — e t e X a run.:1-....|.:..|.L.-|..!.I-..-I..--.|L.ul...r1--:.....--ulhn...lul...|-.u .m .m ..l. C e . a m w n em U r. 0 IN: .m 1 M VA 6 W m a .m 0 0 D a K C P d C T} \2 x) U u m a h "l Jr‘séi. O 4 ta. .‘n ..L .. C r it , the concentration of enzyme in the above reactions influence the equilibrium concentrations of LAB deem * S e 0:: at V; m? mm Wm .ma ) 2 ( d .7 ...
View Full Document

This test prep was uploaded on 02/21/2008 for the course BIO CHEM 153A taught by Professor Staff during the Spring '06 term at UCLA.

Page1 / 7

Biol Chem 153 A Spring 2006 Midterm Exam - Seat # _ Last...

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online