Triose-P isomerase Enolase

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1 Select the single best answer. 1 onsider the catabolism of glucose to carbon dioxide and water. In this metabolic direction, which of these enzymes catalyzes a reaction where the PRUTS have one more "high-energy" bond than do the substrates? hexokinase enolase succinyl o synthetase pyruvate kinase aldolase 2 Refer to the "Truncated Metabolic Map" which accompanies this exam. The numbers in the first row of the table below refer to enzymes in glycolysis shown on that map. Which names of enzymes correctly match each of the numbers? Phosphoglucoisomerase ldolase Lactate dehydrogenase exokinase ldolase nolase exokinase Triose-P isomerase Pyruvate kinase Phosphoglucoisomerase Triose-P isomerase nolase exokinase Glyceraldehyde--P dehydrogenase Pyruvate kinase Ubiquinol (= reduced coenzyme Q): is a component of complex IV in the respiratory chain. carries electrons from complex II to complex III in the respiratory chain. is part of the rotating subunits in TP synthase. is located mainly in the cell (= plasma) membrane of mammalian cells. is part of the proton channel in the TP synthase complex. 4 Per FIV moles of glucose, what is the maximum number of moles of TP and of GTP that can be produced from the catabolism of glucose anaerobically and aerobically? Use values we discussed in lecture. ote that five moles of glucose are being catabolized. naerobic erobic TP GTP TP GTP onsider the conversion of mole of FRUTS 6-PSPT to TW moles of - PSPGLYRT. ow many moles of TP are produced (or utilized) in this conversion? onsider only the overall net change (if any) in TP.

2 + = number of moles of TP produced in this reaction sequence = number of moles of TP utilized in this reaction sequence 0 = no net production or utilization of TP (i.e., the amount of TP remains constant) TP synthase makes TP by using chemical energy directly supplied by: the oxidation of a reduced flavin. a proton gradient across the plasma (= cell) membrane. a proton gradient across the inner mitochondrial membrane. the high-energy bonds of TP. a proton gradient across the outer mitochondrial membrane. 7 Lactose (= milk sugar) is a disaccharide comprised of the monosaccharides galactose and glucose. The structure of lactose is shown. (int, in case you need it: glucose is the unit with the potential aldehyde group.) There are two substrates for the enzyme lactose synthase. Using as analogy an enzyme we have considered in lecture, what is one of these two substrates? (ote: the beta-1,4 bond is synthesized in the same manner as an alpha-1,4 bond in other carbohydrates.) galactose UP-glucose glucose 1-phosphate glucose 6-phosphate glucose 8 What is a structural difference between the two plant polymers starch and cellulose? Starch has fructose monomers, cellulose has glucose monomers. Starch is a dimer comprised of two glucose units, cellulose is a long polymer. The sugar monomers in starch are connected only via alpha-1,4-glycosidic bonds, the sugar monomers in cellulose are connected only via alpha-1,6-glycosidic bonds. The sugar monomers in starch are connected mainly via alpha-1,4-glycosidic bonds, the sugar monomers in cellulose are connected via beta-1,4-glycosidic bonds. ellulose contains -glycosidic bonds, starch contains -glycosidic bonds.

3 9 onsider the conversion of stearic acid to palmitoyl coenzyme. (Stearic acid contains 18 carbon atoms, palmitic acid 16.) Which of the following is the correct order of the first four enzymes for this conversion? synthetase, + dependent dehyrogenase, hydratase, F dependent dehydrogenase + dependent dehyrogenase, hydratase, F dependent dehydrogenase, synthetase synthetase, F dependent dehyrogenase, hydratase, + dependent dehydrogenase F dependent dehyrogenase, hydratase, + dependent dehydrogenase, synthetase F dependent dehyrogenase, synthetase, + dependent dehydrogenase, hydratase 10 major metabolic role of the enzyme glucose 6-phosphatase is in the path leading to: liver glycogen. blood glucose. muscle glycogen. blood lactate. muscle lactate. 11 onsider the following reaction, which is analogous to ones we have considered in lecture So oth substrates and contain a vitamin as part of their structures. ame these two vitamins. niacin and pantothenic acid riboflavin (= 2 ) and niacin riboflavin and thiamine (= 1 ) riboflavin and vitamin pantothenic acid and riboflavin 12 onsider the enzymes shown in the table below. Indicate whether they are located in the cytoplasm () or mitochondria (M) of mammalian cells. conitase Succinyl o synthetase Lactate dehydrogenase Phosphofructokinase M M M M M M M M M M 1 onsider the following reaction which occurs in a biosynthetic pathway for lysine.

4 - X Using as analogy a reaction we have considered in lecture, what is the substrate X? In the metabolic sequence from ISITRT to XLTT, what is the maximum number of moles of TP and of GTP that can be produced per mole of isocitrate being oxidized? Include TP and GTP produced both directly by enzymes in the metabolic sequence and by subsequent oxidative phosphorylation with products produced during the metabolic sequence. Use values for TP yields that were discussed in lecture. onsider only metabolic pathways covered in lecture. TP GTP The respiratory chain in eukaryotic cells, which is located in the R, transports S from the T into the X. The S return(s) to the T via the Y.

5 R S T X Y intermembrane TP intermembrane matrix proton channel space space outer mitochondrial electrons matrix cytosol respiratory membrane chain inner mitochondrial protons cytosol intermembrane proton channel membrane space inner mitochondrial protons matrix intermembrane proton channel membrane space cell (= plasma) electrons intermembrane matrix respiratory membrane space chain 16 The reason that large quantitites of lactate are produced during strenuous exercise is that: acetyl coenzyme is being oxidized to 2. in the matrix must be reoxidized. in the cytoplasm must be reoxidized. a substrate for the glycogen synthase reaction must be available. the inner mitochondrial membrane is permeable to and F new street drug was tested on rats and found to lead to impairment of oxygen consumption. The effect of the drug was tested further on oxygen consumption by isolated intact liver mitochondria. The medium contained phosphate buffer at p 7.4, P, Mg 2+, and selected substrates. In this system, the drug inhibited oxygen uptake when succinate was substrate but not when malate, isocitrate, or 2- ketoglutarate were substrates. The specific site of inhibition of the drug is likely: cytochrome c oxidase (complex IV). TP synthase. -oq oxidoreductase (complex I). succinate-oq oxidoreductase (complex II). malate dehydrogenase. 18 Refer to the "Truncated Metabolic Map" which accompanies this exam. The numbers in the first row of the table below refer to enzymes in and around the T cycle shown on that map. Which names of enzymes correctly match each of the numbers? itrate synthase Isocitrate dehydrogenase Fumarase Pyruvate dehydrogenase alpha-ketoglutarate Succinate dehydrogenase complex dehydrogenase complex conitase alpha-ketoglutarate Succinyl o synthetase dehydrogenase complex itrate synthase conitase Fumarase Pyruvate dehydrogenase complex Isocitrate dehydrogenase Malate dehydrogenase The next three questions refer to the pages entitled "Truncated Metabolic Map." (ote that more than one answer may be possible; only the answer from this previous exam is given.) 19 Which enzyme is directly involved in the transfer of a fatty acyl group across the inner mitochondrial membrane?

6 Which enzyme catalyzes the production of TP in the glycolytic pathway? Which enzyme catalyzes the addition of water across a - double bond? The next three questions refer to structures shown on the pages "Structures of Metabolites." 22 onsider the following pathway that is comprised of two sequential reactions: So So What is the compound? J4 1 F5 K 4 2 ne of the substrates of the glyceraldehyde -phosphate dehydrogenase reaction is: M8 L2 2 J1 24 Which of the following is a substrate for one of the enzymes in the beta-oxidation pathway? F2 J4 M L2 J2

7 25 eta-oxidation of one mole of the following unusual fatty acyl o to four moles of acetyl o yields how many moles of F2 and? (lthough you have not seen the beta-oxidation of this type of unusual fatty acid, the enzymic sequence is the same as that for saturated fatty acids, except that some of the intermediates of course do not have to be formed.) F So (Three beta-oxidation cycles produce 4 acetyl o. The first cycle skips the F-linked dehydrogenase. The second cycle is complete. The third cycle skips the F-linked dehydrogenase and the hydratase. This is outlined on the next page.)

8 In the reactions shown below: "" means that + is reduced to + + ; "F" means that F is reduced to F 2. So 2 So So os So + So F So 2 So So os So + So So 2 os 2 So

9 2 TRUT MTLI MP γ 15 PPi Glucose Glc-6-P 28 Glycerol--P Mitochondria Mitochondria Lactate 2 Glc-1-P UPGlc Fru-6-P Fru-1,6-P in some species Glycogen (alpha1,4) Glyceraldehyde--P -P-Glycerate 2-P-Glycerate P-nolpyruvate Pyruvate Pentose-P pathway 1,-bisP-Glycerate Pi Palmitate (16) xal(o)acetate 4 Malate Malonyl P Malonyl o Repeat until 16 Fatty acyl P 2 noyl P -ydroxyacyl P 5 -Ketoacyl P nz cetyl-nz cetyl o holesterol itrate 45 Pyruvate cetyl o xal(o)acetate itrate Isocitrate 2-Ketoglutarate 60 Malate ytoplasm ytoplasm ytoplasm ytoplasm Ketone bodies T ycle cetyl o FM FeS Fumarate ytoplasm Fatty acid -Ketoacyl o Succinate MP PP i Fatty acyl o (etc.) Glycerol--P imm ytoplasm ihydroxyacetone-p oq Succinyl o Fatty acyl o Fatty acyl carnitine -ydroxyacyl o yt b,c 1 FeS 57 2 P i ihydroxyacetone-p arnitine yt c o 52 γ 50 o arnitine Fatty acyl o 51 noyl o yt a,a u Mitochondria Mitochondria Mitochondria F 2

10 MioS 0 γ Structures of Metabolites (Identifying letter/number is LW the respective structure) pg. 1 2 = 2 P - - ( ) 10-2 F1 F2 F F4 F So R So P = R 2 P = 2 P P= 2 or - G1 G2 G G4 G5 G6 G7 G8 G9 P= 2 2 P = 2 S 2 P P - - = P 1 2 4

11 MioS 0 γ Structures of Metabolites (Identifying letter/number is LW the respective structure) pg. 2 ) 10 2 P - - P P P - 2 P - 2 P J1 J2 J J4-2 P - S P P - - = P 2 S 2 P P - - = P 2 K1 K2 K - 2 P - - P - P - 2 P - - P - 2 P P = L1 L2 L L4 L5 (

12 MioS 0 γ Structures of Metabolites (Identifying letter/number is LW the respective structure) pg. = P P= = P = 2 P = P P - - M1 M2 M M4 M5 M6 M7 M8 2 - P - + P P - 2 P - - P - P - 2 P - P P P= - - P P - - So R So R P1 P2 P P4 P5

Yield of energy from glucose

Paper : Module : 05 Yield of Energy from Glucose Principal Investigator, Paper Coordinator and Content Writer Prof. Ramesh Kothari, Professor Dept. of Biosciences, Saurashtra University, Rajkot - 360005