BCHS 3305          Exam #4                                            12/08/08

Multiple-Choice.  Each correct answer gets two points.  Each wrong (or no) answer gets zero point without any extra penalty.

 

o  Coenzyme A contains (#1) ____ as part of its structural component. 

[(a) adenine;  (b) guanine;  (c) cytosine;  (d) uracil;  (e) none of the above]

o  The IMP synthetic pathway  requires 11 enzymes: (1) ribose phosphate pyrophosphokinase, (2) amidophosphoribosyl transferase,  (3) glycinamide ribotide synthetase, (4) glycinamide ribotide transformylase, (5) formylglycinamidine ribotide synthetase, (6) 5-aminoimidazole ribotide synthetase, (7) 5-aminoimidazole ribotide carboxylase, (8) 5-aminoimidazole-4-(N-succinylocarboxamide) ribotide synthetase, (9) adenylosuccinate lyase, (10) 5-aminoimidazole-4-carboxamide robitide transformylase, and (11) inosine monophosphate cyclohydrolase.  In addition, the synthesis of AMP from IMP requires (12) adenylosuccinate synthetase and (13) adenylosuccinate lyase whereas the formation of GMP from IMP involves (14) IMP dehydrogenase and (15) GMP synthase.

·         Enzyme (8) requires (#2) ____ as a substrate (or substrates).  [(a) glutamine but not ATP;  (b) glutamine and ATP;  (c) aspartate but no nucleoside triphosphate;  (d) aspartate and ATP;  (e) aspartate and GTP]

·         Enzyme (12) requires (#3) _____ as a substrate (or substrates).  [(a) glutamine but not ATP;  (b) glutamine and ATP;  (c) aspartate but no nucleoside triphosphate;  (d) aspartate and ATP;  (e) aspartate and GTP]

·         For the synthesis of one molecule of IMP from one α-D-ribose-5-phosphate, a total of (#4) _____ molecules of ATP are required as substrates.  [(a) 3; (b) 4; (c) 5; (d) 6; (e) 7]

·         In the step-wise synthesis of IMP from α-D-ribose-5-phosphate by enzymes 1 through 11, the first enzyme that generates a product with a heterocyclic attachment to the ribose is (#5) _____.  [(a) enzyme (5);  (b) enzyme (6);  (c) enzyme (7);  (d) enzyme (8);  (e) none of the above]

·         Enzyme (14) catalyzes the conversion of IMP to XMP.  The product XMP is at (#6) _____ that of the substrate IMP.  [(a) the same oxidation level as;  (b) a higher oxidation level than;  (c) a lower oxidation level than]

·         The enzyme (2) is inhibited by (#7) _____.  [(a) AMP and GMP but not XMP;  (b) AMP and XMP but not GMP;  (c) XMP and GMP but not AMP;  (d) AMP, GMP, and XMP]

o  In purine,

·         the N at position 9 is derived from the (#8) ____.  [(a) amine group of glycine; (b) amine group of aspartate; (c) amine group of glutamine, (d) amide group of glutamine]

·         the C at position 4 is derived from the (#9) ____.  [(a) HCO3; amine group of glycine; (b) formate; (c) glycine]

o  The reaction  AMP + ATP ADP + ADP can be catalyzed by (#10) _____.  [(a) nucleoside monophosphate kinase but not adenylate kinase; (b) adenylate kinase but not nucleoside monophosphate kinase ; (c) either adenylate kinase or nucleoside monophosphate kinase]

o  For the degradation of purines, only two ribonucleotides are precursors for the formation of hypoxanthine.  These two ribonucleotides are (#11) _____  [(a) AMP and GMP; (b) AMP and IMP; (c) IMP and XMP; (d) IMP and GMP; (e) GMP and XMP].

o  For the conversion of xanthosine to xanthine by purine nucleoside phosphorylase, (#12) _____ is released as one of the products.  [(a) ribose; (b) ribose-5-P; (c) ribose-1-P].

o  The biosynthesis of UMP from glutamine and HCO3 requires orotidine monophosphate decarboxylase and five additional enzymes, namely (a) carbamoyl phosphate synthetase II, (b) aspartate transcarbamoylase, (c) dihydroorotase, (d) dihydroorotate dehydrogenase, and (e) orotate phosphoribosyl transferase.   

·         PRPP is required as a substrate by enzyme (#13) _____.

·         In addition to carbamoyl phosphate synthetase II, the enzyme (#14) _____ can also produce Pi as a product.

·         The first cyclic six-member ring pyrimidine product is formed by the reaction catalyzed by the enzyme (#15) _____.

o  The enzymatic conversion of uridine phosphate to cytidine phosphate requires (#16) _____ as a substrate.  [(a) UMP;  (b) UDP;  (c) UTP;  (d) any one of the above three]

o  In animals, carbamoyl phosphate synthetase II is inhibited by (#17) _____.  [(a) UMP or UDP but not UTP;  (b) UDP or UTP but not UMP;  (c) UMP or UTP but not UDP;  (d) UMP, UDP, or UTP]

o  For the biosynthesis of pyrimidine as shown below,

·         the N at position 3 is derived from the (#18) _____. [(a) amine group of glycine; (b) amine group of aspartate; (c) amine group of glutamine, (d) amide group of glutamine]

·         the carbon at position 4 is derived from (#19) _____. [(a) glutamate; (b) aspartate; (c) HCO3-; (d) none of the above]

o  For the conversion of dUMP to dTMP, the enzyme thymidylate synthase requires (#20) _____ as a substrate. [(a) N5-methyl-THF, (b) N5,N10-methylene-THF, (c) N5,N10-methenyl-THF, (d) N5-formyl-THF, (e) N10-formyl-THF] (with THF = tetrahydrofolate)

o  In enzymatic degradation of UMP, the heterocyclic pyrimidine ring is first opened to form a non-cyclic product by the enzyme (#21) _____.  [(a) dihydrouracil dehydrogenase; (b) hydropyrimidine hydratase; (c) β-ureidopropionase; (d) aminotransferase]

o  For the step-wise enzymatic degradation of CMP, cytidine (#22) _____ be directly converted to cytosine.  [(a) can;  (b) cannot]

o  In order for the nitrogenase-catalyzed formation of 2 NH3 from one N2 to occur, a total of (#23) _____ ATP molecules are utilized.  [(a) 2; (b) 4; (c) 8; (d) 16; (e) 32]

o  Hydrazine is at (#24) _____  that of diimine.  [(a) a higher level of oxidation than;  (b) the same level of oxidation as; (c) a lower level of oxidation than]

o  During the sequence of the reactions catalyzed by nitrogenase, the (Fe-Protein)ox component is reduced to the (Fe-Protein)red form.  Subsequently [(a) 2 ATP bind to (Fe-Protein)red, and then (b) the (Fe-Protein)red-bound ATPs are hydrolyzed.]  The step of (#25) _____ (choose between a and b) induces a conformational change of the (Fe-Protein)red, converting it from a weak reductant with E’ of -0.29 V to a stronger reductant with E’ of -0.40 V.

o  The actual step-wise reduction of N2 to 2 NH3 is catalyzed by the (#26) _____ component of nitrogenase.  [(a) Fe-Protein;  (b) Mo-Fe-Protein]

o  (#27) _____ can catalyze the incorporation of the N of NH3 into cabamoyl phosphate.  [(a) cabamoyl phosphate synthatase I but not cabamoyl phosphate synthatase II; (b) cabamoyl phosphate synthatase II but not cabamoyl phosphate synthatase I; (c) either cabamoyl phosphate synthatase I or cabamoyl phosphate synthatase II]

o  In E. coil, a higher level of -ketoglutarate will lead to enhanced (#28) _____ of a tyrosine residue in a PH protein in association with adenylyltransferase.  [(a) adenylation but not uridylation; (b) uridylation but not adenylation; (c) either adenylation or uridylation; (d) neither adenylation nor uridylation]

o  The step-wise conversion of NO3 to NO2 and then to NH4+ is referred to as (#29) _____.  [(a) ammonification;  (b) anammox; (c) nitrification; (d) denitrification; (e) nitrogen fixation]

o  Nitrogen fixation is an (#30) _____ process.  [(a) aerobic;  (b) anaerobic]

o  In mammals, acetyl-CoA (#31) _____ be metabolically converted to pyruvate.  [(a) can;  (b) cannot]

o  In mammals, acetyl-CoA can be oxidized to CO2 and H2O.  The TCA cycle enzymes are directly responsible for the oxidation of acetyl-CoA to 2 CO2.  The actual formation of H2O by oxidation of the reducing equivalents derived from acetyl-CoA (in term of hydrogen) is performed by enzymes in (#32) _____.  [(a) TCA cycle; (b) oxidative phosphorylation]

o  In mammals, pyruvate (#33) _____ a precursor for the biosynthesis of fatty acids.  [(a) is;  (b) is not]

o  A major consumption of ATP in brain is to pump (#34) _____ the brain cells.   [(a) Na+ out and K+ in; (b) K + out and Na + in; (c) both Na+ and K+ in; (d) both Na+ and K+ out]

o  A major source of glucose for the consumption by brain cells is from (#35) _____.  [(a) glycogen degradation;  (b) glucoeogenesis in brain cells;  (c) glucose carried to brain cells by blood flows;  (d) all of the above;  (e) none of the above]

o  A major source of glucose for the consumption by muscle cells is from (#36) _____.  [(a) glycogen degradation;  (b) glucoeogenesis in muscle cells;  (c) glucose carried to muscle cells by blood flows;  (d) all of the above;  (e) none of the above]

o  Under heavy exercise, muscle converts glucose primarily to (#37) _____ as end product(s) through an anaerobic process.  [(a) pyruvate;  (b) acetyl-CoA;  (c) lactate;  (d) H2O and CO2]

o  In heart tissue, glucose undergoes catabolism to the end product(s) (#38) _____.  [(a) pyruvate;  (b) acetyl-CoA;  (c) lactate;  (d) H2O and CO2]

o  Carbohydrate metabolism is linked to fatty acid metabolism through glycerol-3-phosphate, which is essential to the synthesis of (#39) _____.  [(a) fatty acids;  (b) triglycerides;  (c) cholesterol;  (d) all of the above;  (e) none of the above]

o  Liver is (#40) _____ converting ketone bodies to acetyl-CoA.  [(a) incapable of;  (b) highly active in] 

o  The normal blood glucose level in human is (#41) _____ mM.  [(a) ~ 2;  (b) ~5;  (c) ~10]

o  According to the Cori Cycle, a major function of liver is to convert lactate to pyruvate and then back to glucose.  This gluconeogenesis process requires ATP, which is primarily generated in liver by (#42) _____.  [(a) glycolysis;  (b) TCA cycle;  (c) oxidative phosphorylation;  (d) none of the above]

o  In muscle, glucose (#43) _____ be efficiently converted to pyruvate and then to alanine.  [(a) can;  (b) cannot]

o  In the adenylate cyclase signaling system,

·         The Gsα•GTP is capable of (#44) _____.  [(a) activating adenylate cyclase but not GTP hydrolysis;  (b) GTP hydrolysis but not activating adenylate cyclase;  (c) activating adenylate cyclase and GTP hydrolysis; (d) neither activating adenylate cyclase nor GTP hydrolysis]

·         The dissociation of Gsβγ from Gsα is induced by the (#45) _____.  [(a) binding of GTP; (b) hydrolysis of GTP]

·         cAMP binds to the (#46) _____ subunit of the R2C2 adenylate cylase.  [(a) monomeric R;  (b) dimeric R2;  (c) monomeric C; (d) dimeric C2]

o  In the resting state and monomer form of a usual receptor tyrosine kinase before the binding of any hormone, the intracellular C-ternimal domain is (#47) _____.  [(a) un-phosphorylated but active as a tyrosine kinase;  (b) un-phosphorylated and inactive as a tyrosine kinase;  (c) phosphorylated but inactive as a tyrosine kinase;  (d) phosphorylated and active as a tyrosine kinase]

o  The resting state and inactive form of an insulin receptor is in the (#48) _____ form.  [(a) monomeric;  (b) dimeric]

o  In the phosphoinositide pathway,

·         the phospholipase C is activated by (#49) _____.  [(a) phosphatidylinositol-4,5-bisphosphate (PIP2);  (b) inositol-1,4,5-triphosphate (IP3);  (c) 1,2-diacylglycerol;  (d) Gqαβγ;  (e) Gqα•GTP]

·         IP3 binds to a Ca2+ transport channel in endoplasmic reticulum to (#50) _____ the cytosolic Ca2+ level.  [(a) increase;  (b) decrease]