BCHS 3305                                                 Exam #3 (Answers at end)                                                                   11/09/09

 

Multiple-Choice.  Choose one answer for each question.  Each correct answer gets two points.  Each wrong answer or no answer gets zero point but no extra penalty.

On the answer sheet, identify (a) your name AND (b) the last four digits of your UH student #.

 

·   The transport of an acyl carnitine from cytosol to mitochondrial matrix is directly coupled to the transport of a (#1) ____ from mitochondrial matrix to cytosol by an antiport system.

[(A) acyl-CoA;  (B) CoA;  (C) fatty acid;  (D) carnitine]

·   Carnitine palmitoyl transferase II is on the surface of the mitochondrial inner membrane that faces the  (#2) ____.

[(A) cytosol;  (B) mitochondrial matrix]

·   The enoyl-CoA metabolite in the pathway of fatty acid b-oxidation is in the (#3) ____ configuration.

[(A) D2-cis;  (B) D2-trans;  (C) D3-cis;  (D) D3-trans]

·   The complete oxidation of decanoic acid (CH3-(CH2)8-COOH) to CO2 and H2O by β–oxidation, TCA cycle, and oxidative phosphorylation will produce a NET gain of (#4) ____ molecules of ATP.  (Note: GTP is considered the same as ATP)

[(A) 78;  (B) 79;  (C) 80;  (D) 81;  (E) none of the above]

·   The enzyme enoyl-CoA isomerase (#5) ____ convert the substrate I to the product II.

[(A) can;  (B) cannot]

            I                                                                  II

·   The reaction as shown below (#6) ____ be catalyzed by an isomerase that we have discussed in our class.      [(A) can;  (B) cannot]

·   The hydroxy group in the hydroxyacyl-ACP metabolite in normal fatty acid biosynthesis pathway assumes the (#7) ____ configuration.

[(A) L-a;  (B) L-b;  (C) D-a;  (D) D-b]

·   In ketone body biosynthesis, the hydroxy group of the hydroxybutyrate (derived from acetoacetate) is in the (#8) ____ configuration.

[ (A) L-a;  (B) L-b;  (C) D-a;  (D) D-b]

·   The enzyme propionyl-CoA carboxylase catalyzes the conversion of propionyl-CoA to the (#9) ____ form of methylmalonyl-CoA.

[(A) S;  (B) R]

·   In fatty acid b-oxidation, the conversion of a saturated fatty acyl-CoA to enoyl-CoA requires (#10) ____ as a reactant, and the conversion of hydroxyacyl-CoA to ketoacyl-CoA requires (#11) ____ as a reactant.

[(A) FAD;  (B) FADH2;  (C) NAD+;  (D) NADH + H+;  (E) none of the above]

·   For fatty acid biosynthesis in cytosol, the conversion of acetoacetyl-ACP to hydroxybutyryl-ACP requires (#12) ____ as a reactant, and the conversion of butenoyl-ACP to butyryl-ACP requires (#13) ____ as a reactant.

[(A) NAD+;  (B) NADH + H+;  (C) NADP+;  (D) NADPH + H+;  (E) none of the above]

·   In the following reaction catalyzed by b-ketoacyl-ACP synthase one particular carbon in the reactant malonyl-ACP is labeled with an isotope marker as indicated by the asterisk.  This carbon will be recovered at position (#14)  ____ in the product as shown below.

                                                                             [A      B  C  D               E]

·   Following one cycle of the tricarboxylate transport system as shown below, there will be a net gain of one molecule of acetyl-CoA and one molecule of (#15) ____ in the cytosol.  Also there will be a net loss of (#16) ____ in the cytosol.

·        

[(A) NAD+ ;  (B) NADH;  (C) NADP+;  (D) NADPH]

 

·   For further elongation of palmitate in mitochondria, all metabolites are activated in forming a thioester linkage with (#17) ____.

[(A) CoA;  (B) ACP]

·   A desaturase (#18) ____ catalyze the following reaction:      [(A) can;  (B) cannot]

·   Linoleate (18:2, D9,D12) is an essential fatty acid for human because human cannot generate (#19) ____ double bond.

   [(A) the D9;  (B) the D12;  (C) either the D9 or the D12]

·   The conversion of β–hydroxymethylglutaryl-CoA to mevalonate requires (#20) ____ as co-substrate.

   (A) one NADPH;  (B) two NADPH; (C) one NADH;  (D) two NADH;  (E) none of the above]

 

 

 

·   The molecule as shown below is (#21) ____.

[(A) 5-pyrophosphomevalonate;  (B) isopentenyl pyrophosphate;  (C) dimethylallyl pyrophosphate;  (D) none of the above]

·   The addition of one farnesyl pyrophosphate to another farnesyl pyrophosphate to form a squalene is a (#22) ____ condensation reaction.

[(A) head-to-head;  (B) head-to-tail]

·   The conversion of dihydroxyacetone phosphate to glycerol-3-phosphate requires (#23) ____, and the conversion of acyl-dihydroxyacetone phosphate to lysophosphatidic acid requires (#24) ____.     [(A) NADH;  (B) NAD+;  (C) NADPH;  (D) NADP+]

·   Phosphoethanolamine has to be activated by (#25) ____ before reacting with diacylglycerol to form phosphatidylethanolamine.

[(A) ATP;  (B) CTP]

·    The following molecule (#26) ____ lanosterol.     [(A) is;  (B) is not]

·   The excreted end product from the amino group of amino acids is (#27) ____ in uricotelic animals.

[(A) ammonia;  (B) uric acid;  (C) urea]

·   For the catabolism of amino acids, initially a transamination reaction takes place between a variety of amino acids and (#28) ____ to form a single amino acid product for further deamination.

[(A) a-ketobutyrate;  (B) a-ketoglutarate;  (C) acetoacetate]

·   Glutamate dehydrogenase is an allosteric enzyme with (#29) ____ as an activator, and (#30) ____ is an inhibitor.

[(A) GMP;  (B) GDP;  (C) GTP;  (D) none of the above]

·   The molecule as shown below is a(n) (#31) _____.

[(A) aldimine;  (B) quinonoid;  (C) ketimine]
 

·   Pyridoxine (#32) ____ an active cofactor for the enzyme aminotransferase.

[(A) is;  (B) is not]

·   Serine dehydratase can catalyze the breakdown of serine to form ammonia and (#33) ____ as products.

[(A) a-ketobutyrate;  (B) a-ketoglutarate;  (C) acetoacetate;  (D) pyruvate;  (E) none of the above]

·   Eukaryotes have two forms of carbamoyl phosphate synthetase, namely the mitochondrial CPS I and the cytosolic CPS II, of which only the (#34) ____ participates in the synthesis of urea.

[(A) CPS I;  (B) CPS II]

·   The condensation of citrulline and aspartate to form argininosuccinate by the catalysis of argininosuccinate synthetase is driven by energy derived from the hydrolysis of(#35)  ____.

[(A) ATP ® ADP + Pi;  (B) ATP ® AMP + PPi]

·   Following the urea cycle, the nitrogen atom in ammonia is preserved in (#36) ____.

[(A) citrulline only;  (B) ariginino-succinate only;  (C) urea only; (D) all of the above;  (E) none of A, B, or C]

·   For the regulation of the urea cycle, enhanced degradation of amino acids will step-wise lead to (#37) ____ activity of carbamoyl phosphate synthetase I.

[(A) a lower;  (B) a higher;  (C) no significant change of]

·   The cellular level of citrulline in cytosol (#38) ____ regulatory role on the efficiency of urea cycle.

[(A) has a;  (B) has no]

·   Following is a list of catabolites derived from amino acids.

[(A) Acetyl-CoA;  (B) Acetoacetate;  (C) Pyruvate;  (D) Fumarate;  (E) Succinyl-CoA]

   For the known degradation pathway(s) of a given amino acid, ONE CATABOLITE from the above list will be generated BEFORE the possible formation of any other catabolites shown above.  Choose from the above list to complete the following statements:

   [Example:  Threonine undergoes one degradation pathway to first form    A   , and another pathway to first form    C   .  (Note: For two answers, list them in alphabetic order.)]

·   For ketone body formation, the enzyme b-hydroxymethylglutaryl-CoA lyase in (#44) ____ converts b-hydroxymethylglutaryl-CoA to acetoacetate.

[(A) cytosol;  (B) mitochondria]

·   The active one-carbon unit in N5,N10-methylene-THF is at (#45) ____ that in N5,N10-methenyl-THF.   (where THF = tetrahydrofolate)

[(A) a higher oxidation state than;  (B) the same oxidation state as;  (C) a lower oxidation state than]

·   The following molecule is (#46) ____ (where R is –benzoyl-(glutamate)1-6)

[(A) N5-methyl-THF;  (B) N5-formyl-THF;  (C) N5-formimino-THF;  (D) none of the above]

·   The conversion of glycine to serine requires (#47) ____ as a one-carbon donor.

[(A) N5-methyl-THF;  (B) N5,N10-methylene-THF;  (C) N5,N10-methenyl-THF;  (D) N5-formyl-THF;  (E) N10-formyl-THF]

·   For the shortest biosynthetic pathway, (#48) ____ is a precursor for the biosynthesis of proline, and (#49) ____ is a precursor for the biosynthesis of asparagine.

[(A) α-Ketoglutarate;  (B) 3-Phosphoenolpyruvate;  (C) Oxaloacetate;  (D) Pyruvate]

·   For human, tyrosine (#50) ____ an essential amino acid.

[(A) is;  (B) is not]

 

Answers: (1-D), (2-B), (3-B), (4-B), (5-A), (6-A), (7-D), (8-D), (9-A), (10-A), (11-C), (12-D), (13-D), (14-C), (15-D), (16-B), (17-A), (18-B), (19-B), (20-B), (21-B), (22-A), (23-A), (24-C), (25-B), (26-B), (27-B), (28-B), (29-B), (30-C), (31-A), (32-B), (33-D), (34-A), (35-B), (36-D), (37-B), (38-A), (39-B), (40-D), (41-A), (42-E), (43-E), (44-B), (45-C), (46-C), (47-B), (48-A), (49-C), (50-B)