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Spring '07 exam 2 - BBMB 405 Exam 2 March 9 2007 Name Z...

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Unformatted text preview: BBMB 405 Exam 2 March 9, 2007 Name Z l :‘L—prW 1. (2 pts) What is the role of phospholipase A in the synthesis of prostaglandin E ? W754” W(C'2054§<fi’1 ‘ 65 P451 Zr: PM WA \ F“ 6% P‘gavdé J \3 2. (3 pts) State a specific reaction of prostaglandin biosynthesis that is inhibited by aspirin to alleviate Féé a fever and/or headache in your body“ Name the inhibited enzyme. <~ 3. FGW e cvconverzidn E 44—9 gm féw (4 pts) Is biotin needed forth of glutamine to acetyl— —CoA in your body? Justify your answer. Yes or No GM Uh; WJrM-«e o< K0 ——- >——> ma? r5 F—a fro % 3 ' ”W W 691” W-- Mawz 43.34.451.42. agefizp’“, 4. (4 pts) Ubiquitin is an ATP— —dependent prot se that rapidly hydrolyzes proteins that are marked for degradation E 23.45; g . Defend your anSWer True or False ' mm, 1&va % W _ 74 W fl—Tf‘ W’f 5. Within a few days after a fast begins, nitrogen excretion accelerates to a hi gher—than—normal level. After a few weeks, the rate of nitrogen excretion falls to a lower level and continues at this low rate. However, after the lipid stores have been depleted, nitrogen excretion rises to a high level. (3 pts) a. What events trigger the initial surge of nitrogen excretion? WW,MEWW15 52% (3 pts) c. Explain the increase in nitrogen excretion when the lipid stores have been depleted. mm W M Wm % W _ M W 6. (3 pts) Cysteine and cystine. Most cytosolic proteins lack disulfide bonds, whereas extracellular proteins usually contain them. Why? W W (gt/W MKS-5:642 559 “Tie MW 44.2% ' " .9. 5 H «I, _ 95,. W 7. (5 pts) What is the activated reactant in each of the following biosyntheses? a. Phosphatidylinositol from inositol C D P——D @413 b. Phosphatidylethanolamine from ethanolamine C— D P‘ F c. Ceramide from sphingosine __—_E_£L d. Sphingomyelin from ceramide g z I 213- M4 .& e. Cerebroside from ceramide (z D [L 2;: {/L UD (944/6 8. (2 pts) What is the distribution of isotopic labeling in cholesterol synthesized from each of the following precursors? ('4 flag I f ‘ a. Mevalonate labeled with MC in its carboxyl carbon atom M0 6 W my me . b. Malonyl-CoA labeled with 14C in its carboxyl carbon atom Ma 0 (a) W I'+ J 0 Cl 5 9. Mice were divided into four groups, two of which were fed a normal diet and two of which were fed a cholesterol—rich diet. HMG—CoA reductase mRNA and protein from liver then were isolated and quantified. Graph A shows the results of the mRNA isolation. f? ACtln mRNA D HMG-CoA reductase mRNA 1.00 Amount of mRNA_ (arbitrary unIts) Control control Cholesterol fed Cholesterol fed (A) mice mice mice mice a. (2 pts) What is the effect of cholesterol feeding on the amount of HMG- CoA reductase mRNA? 2 E g g : HMG—CoA reductase protein was isolated by precipitation with a monoclonal antibody to HMG— CoA reductase. The amount of HMG—CoA protein in each group is shown in graph B. l .00 0.67 Amount of HMG-CoA reductase proteln (arbItrary unIts) 9 bi bi Control mice Cholesterol-fed mice A m v b. (2 pts) What is the effect of the cholesterol diet on the amount of‘HMG—CoA reductase protein? I WMW W WWW c. (2 pts) Why is this reSult surprising in light of the results in graph A? 04“ W M /2 1/ # Mm W 4.377% cm ’ Vi” d. (2 pts) Suggest possible explanations for the results in graph B. Wé/Zw/c m RAJ/4f MW “e 64p 14/14 5 , ’ 14' m 3 10. (3 pts) Tyrosine is normally a nonessential amino acid, but individuals with a genetic defect in phenylalanine hydroxylase require tyrosine in their diet for normal growth. Explain. W¢§Wfiw [(9% w WWW "l WJW W~ <SF5'): ll. (3 pts) In contracting skeletal muscle, the concentrat1on o p osphocreatine drops while the concentration of ATP remains fairly constant. Explain how this happens J CPK::W%0WW ’e'TFvfiWI-moée/ W cha." '64...” (”by P 12. (3 pts) State three important metabolic fates of alanine when it arrives at your liver after consuming a three-egg omelet. WMRAV flew (.2 I) C 3%. 9g}: flawlia ca, (ax/Wéflv) 61/6 at, ~43 (3%.; W away GAL—as l3. (5 pts) Lovastatin or Mevacor® is expected to have an impact on your blood cholesterol \) W concentration if you consume it. / . l W us i our answer C” True or False I t fy y W W W HM$~Q74 W m 89> (5 pts) Brain 1s a net producer of glutamine; that is, more glutamine leaves the brain than the amount of glutamine that arrives. Show how the carbon of glutamine may be derived from glucose. 15. (8 pts) Match the appropriate components or properties in the right column with the lipoproteins in the left column. More than one match is possible. a. Chylomicron 2:); 5’4 1. Transports endogenous cholesterol esters b. VLDL (, S :7; 4 2. Transports dietary triacylglycerols c. LDL l, i 3. Transports endogenous triacylglycerols d. HDL z _5 , 2 4. Is degraded by lipoprotein lipase 5. Is taken up by cells via receptor— mediated mechanisms 6. Is a precursor of LDL 7. May remove cholesterol from cells 16. (8 pts) State the principal organ or tissue of your body that carries out the following metabolic processes: a. Synthesis of urease b. Conversion of phenylalanine to epinephrine d. Synthesis of chymotrypsinogenw e. Conversion of tyrosine to dopamine wigs“ WW f. Synthesis of pepsinogenw‘ g. Synthesis of lys1new_€£_w/ W h. Synthesis of bilirubin diglucuronidew 17. (4 pts) If 15N—labeled aspartate is fed to your pet dog, many other amino acids labeled with 15N quickly appear in the blood. Explain this observation. Viz/U (bf fW/Igwgm 18. (10 pts) Fill in the blanks: a. Reductive amina 'on of a—ketoglutarate requires what coenzyme? Affij) iE) H b. In mammals urea synthesis occurs in what organ? MM c. What coenzyme pr itamin is eede for atransamination reaction in liver? MW , J vim ”5‘4 d. l. a e t 0 amino acids that can be synthesize by transa ' ation of TCA cycle intermediates: and 07179- e. acid that is synthesized by the oxida ion (NAD+) of 3—phosphoglycerate (P- h O—CHz—CHOH—COO‘ followed by a transamination reaction and then hydrolysis of the phosphoester. f. Indiviggals with phenylketonuria (PKU) are unable to convert Wig, t0 . ‘ g. Maple syrup disease is caused by a deficiency of an oc—ketoacid dehydrogenase in the catabolic pathwa of what amino acid(s)? ( \ N , WWW—4% W: Mug/W h. BilirubiEis a catabolic product of what component of cytochrome c in humans? 19. (4 pts) Why is 5-fluorouracil a useful chemotherapeutic agent for selected cancers? Be specific. (Wm; egg/«1p ——7L‘;J7mo (.7729‘211 JDI-f PH 20. (4 pts) Why is methotrexate a use 111 chemo erapeutic agent for selected cancers? Be specific. W (W .__. “ SOME NW0} 4- gf 21. (3 pts) What is the activated reactant in the biosynthesis of each of the following compounds? a. Phosphoribosylamine . 2 E) f) b. Carbamoylaspartate Q 2 c. Orotidylate (from orotate) O E F F Have a fun and safe Spring Break! ...
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