Spring '05 - EXAM 1 BBMB 405 Name 1(5 pts Indicate how the...

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Unformatted text preview: EXAM 1 BBMB 405 February 11, 2005 Name 1. (5 pts) Indicate how the pentose phosphate pathway participates in maintaining a low concentration of superoxide ions (02‘) in erythrocytes (RBCs) (5.9 47‘ .. ab” \ :- (gm/La 9‘ 09/ 500 3 Uzfl;%fr (PW [TSH SS . g f (#47233 "‘) #51; U [6-0 PWZ L Wir'm 2. (5 pts) Figure 1 shows the first four reactions of the pentose phosphate pathway. Use it to answer the following questions. a. Which reactions produce NADPH? w b. Which reaction produces C02? __E__ c. Which compound is ribose 5-phosphate? / /‘ d. Which compound is 6-phosphogluconate? E Figure 1. Reactions of the pentose phosphate pathway. 3. (4 pts) Liver and other organ tissues contain relatively large quantities of nucleic acids. During digestion, nucleases hydrolyze RNA and DNA, and among the products is ribose—S- phosphate. How can this molecule be used as a metabolic fuel? 3 'E.m—§“P 31 F~é—P -/— Cir-EFF We Wéi/OZ; F—(a-P «mi G~3~Pm mew ’ W,F~L~PmJGaB-P ~53 aoiszo/td; R-E-P—a re -54»- x ~_ - -p F~G~P Lu 3 4&4: rows 7 F~(o-F 2-9-? ,Tk A 4-3-,9 5-44) , ”Ii-‘4’ “‘7 RL4-P—e xk-s—P (tr-3~P 4. (4 pts) You have glucose that is radioactively labeled with 14C at C—1, and you have an extract that contains the enzymes that catalyze the reactions of the glycolytic and the pentose phosphate pathways, along with all the intermediates of the pathways. If the enzymes of the oxidative branch of the pentose phosphate pathway are very active and the only route to form ribose-S—phosphate is from the C—1 labeled glucose, will the ribose contain 14C? h (yes or no) Explain. 4‘; H 0 *cm) 49 c \ umpu \ rump/J lama! l Q‘ C" (4] [email protected] 'Qutoao 7? ”[email protected] are”? e-Fa ”35:70 5. (4 pts) Why is the pentose phosphate pathway more active in cells that are dividing than in cells that are not? yeww—fwwm - z @wamfiw 6. (4 pts) Even if glucose—6—phosphate dehydrogenase is deficient, the synthesis of ribose- 5-phosphate from glucose:6-phosphate can proceed normally. Explain how this is possible. Wm _ We [D'é'fo‘7 F. Q~F “Wt/$7” \A §>G_3_P>fififi>? b F 7. These questions pertain to regulation of glycogen metabolism. For each stimulus, state whether rates of glycogen synthesis and degradation are increased or decreased (Effect) and then explain why the rate change occurs (Why). a. (4 pts) Neural stimulation of skeletal muscle for a vigorous contraction Q1“ 7’ at; - C p . (4 pts Con mption of ' ca ei ted" coffee (e. , Starbucks) on glyco en metabolism in 1' er Effect? 8. (4 pts) Does skeletal muscle release glucose from its glycogen stores to the bl od for transport to your brain? [email protected] (yes or no). Justify your answer. angeuggfle WW WW wG-Ffi MALWZCV'Q‘IO‘ 741M 4143/ &_¢~PWV&AQJ M Cé—Jofll’v—a (Eva-5W) M7 ‘ MWX o’er/7 WW5mV . %[email protected]’€EI:'I?%W ”£27 I 9. (3 pts) Explain why the phosphorolytic cleavage of glycogen is more energetically advantageous than its hydrolytic cleavage. g \ 10. (6 pts) Match the enzymes that degrade glycogen in the left column with the appropriate properties from the right column. More than one answer may be appropriate. a. Pho‘ghorylase 2 [j 1. Is part of a single polypeptide chain with two activities Cleaves a—1,4 glucosidic bonds Releases glucose Releases glucose- 1 -phosph ate Moves three sugar residues from one chain to another 6. Requires ATP b. a—1,6-glucosidase /2 3 c. Transferase /2 R Lg Méww (PPd 1 1. (4 pts) Explain the effect of insulin on the activity of protein phosphatase lAand the subsequent effects on glycogen metabolism MW iW {[email protected]¢ % ‘25 ’ ffl)Mé//éu.; 7%mfizam WWWGZV AM m 9%.. aWazav WW 12. You are studying a patient with McArdle’ s disease, which is caused by a deficiency of phosphorylase in muscle but not in liver. Explain what you would expect to find when you carry out each of the following analyses. Compare to an unaffected person. a. (2 pts) Change in blood lactate concentration after vigorous exercise £7 WW CM W WW 6 41L ‘/ P b. (2 pts) Change 1n blood glucose concentration after administration of epinephrine W gm WWW/(WW {$1.5M Maw 13. (4 pts) Why is the NADH to AD+ ratio unusually high in the liver of a ketotic human baby? 14. 15. 16. (5H3) b. Fatty acid synthesis /) 2,4,5; 4: 7 l7. (4 pts) What is the difference in moles of ATP yield for the oxidation of one mole of the following compounds to C02? r a. Stearic (C—1820) and oleic (C-1821) acids /' ‘3 [FIND/3’2) b. B—Hydroxybutyrate and acetoacetate & - 5—. (IV/3‘10 ’9) c. Palmitate and palmitoyl—CoA g (19' 7M '67“ f) d. Butyrate (04:0) and hexanoatQ(C-6:0) §,s’+l—§ t ’0 = "f U ’90 if , PM? Hr ) 4; /J:/V (4 pts) What two properties make triacylglycerols more efficient than glycogen for the storage of metabolic energy? /. (“waffle/am ' 42M (5 pts) Match the reactant or characteristic in the right column with the appropriate pathway in the left column. . Acyl-CoA Occurs in the cytosol Uses NAD+ D~3-hydroxyacyl derivative involved Pantetheine involved . Malonyl—CoA Single polypeptide with multiple activities involved 8. Uses FAD CAT / - A deficiency of carnitine acyltransferase Ikin human muscle causes cellular damage and recurrent muscle weakness especially during fastng or exercise. A deficiency of the enzyme in the liver causes (a) an enlarged and fatty liver, and (b) a decrease in the concentration of ketone bodies in the blood. Explain the likely causes of these symptoms. NOMPPN“ a. (2 pts) Enlarged and fatty liver A, p 57 " nghfigmif/ffi cm WWE (fig; ’ W%&Tfiéw‘§%&ly~a b. (2 pts) Decrease in blood ketone bodies ‘ i W%@M%a K6 ‘. 5 18. (4 pts) Explain why the catabolism of a C15 fatty acid can lead to the net synthesis of glucose, but the catabolism of a C16 fatty acid cannot. (1—H: >Wn‘1%%?¢>~>é€wfi WAC/61% l Cab/W3 o/MWv— (1—3424 ,3 l9. (3 pts) The light driven reactions of photosynthesis generate two important products used in the Calvin-Benson cycle. What are they AND where do they accumulate in the chloroplast? 20. (6 pts) What are the 4 fates of light energy after absorption by a chlorophyll molecule? 21. (1 pt) The proton gradient in both mitochondria and chloroplasts 1s used for ATP synt which organelle IS the gradient situation largely the result of differences in pH and notn charge separation? W 22. (6 pts) The light-driven reactions of photosynthesis are responsible for several regulatory features. Briefly describe 3 of these. Any 3 0f the following: 1) accumulation of reduced quinines causes phosphorylation of LHCII, dissociation from P511, and transfer to PSI 2) influx of protons into lumen causes efflux of Mg2+ into stroma; many Calvin-Benson enzymes require magnesium 3) influx of protons into lumen causes reduction of protons from stroma; Calvin-Benson cycle enzymes favor alkaline conditions in stroma 4) reduced ferredoxin is able to reduce thioredoxin which then reduces S-S bonds in many Calvin-Benson cycle enzymes thus activating them I 23. Rubisco is a dual-functioning enzyme. a. (2 pts) How does an increase in temperature affect its function? 1) An increase in temperature causes rubisco to fix less C02 and more oxygen- this will lead to photorespiration (wasteful for the plant) b. (2 pts) How does a C4 plant minimize the effects of temperature on rubisco function? 2) C4 plants essentially increase the concentration of CO2 made available to the C-B cycle enzymes by “pumping” it into bundle sheath cells (via malate) which are impermeable to C02 gas; even at higher temperatures, the C-B cycle enzymes now have enough C02 for carbohydrate synthesis ...
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