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Biochem II
Exam 2
| Question | Answer |
|---|---|
| Which of the following enzymes initiates the synthesis of leukotrienes? | 5-lipoxygenase |
| The coenzyme required for all transamination reactions is derived from: | Pyridoxine (vitamin B6) |
| Which of the following intermidiates of the citric acid cycle can be directly used to produce aspartic acid by transamination reaction? | Oxaloacetate |
| Which is the most stable and most reduced from of tetrahydrofolate (THF) carrying a 1-carbon group? | N^5-methyl-THF |
| Which of the following compounds is required to synthesize citrulline from ornithine? | Carbamoyl phosphate |
| Which of the following compounds is needed for the rearrangement of the methyl group of L-methylmalonyl-COA t form succinyl-COA? | Vitamin B12 |
| What is the mechanism of action of the non-sterodial anti-inflammatory drugs (NSAIDs), ibuprofen and aectaminophen? | They are reversible inhibitor of the enzyme cyclo-oxygenase |
| Which of the following compounds is required to synthesize serine from glycine? | Tetrahyfrofolate |
| Which of the following enzymes in the urea cycle produces a glucogenic tricarboxylic acid? | Argininosuccinase |
| Which reaction is catalyzed by the enzyme dihydrofolate reductase? | Formation of tetrahydrofolate (THF) from folic acid |
| Which of the following is true? | Eicosanoids bind to their plasma membrane receptors in order to elict their action |
| What is one of the possible mechanisms by which glucocorticoids regulate inflammation? | Inhibition of the gene expression of the cyclo-oxygenase type 2 (COX2) enzyme |
| Which of the following drugs is an irreversible inhibitor of the enzyme cyclooxygenase? | Aspirin |
| Which of the following reactions can inactivate thromboxanes? | Oxidation of the 15-hydroxyl group to a ketone |
| If an individual was unable to synthesize or obtain tetrahydrofolic acid (THF), the person would probably be deficient in the biosynthesis of which amino acid? | Methionine |
| Which of the following amino acids is NOT derived from glycolysis? | Arginine |
| Which amino acid is the immediate precursor of methionine? | Homocysteine |
| Which of the following compounds incorporates second nitrogen atom of urea in urea cycle? | Aspartate |
| Which of the following compounds can block deoxythymidylate monophosphate (dTMP) biosynthesis? | 5-Flourouracil |
| If a person's urine contains unusually high concentrations of urea, which one of the following diets has he or she probably been eating recently? | Very low carbohydrate, very high protein |
| Which of the following compounds contributes one-carbon unit for the reaction involving one-carbon unit transfer? | Serine, Formate, Histidine |
| True or False: Glutamate dehydrogenase is a cytosolic enzyme. | False |
| Which of the following are required to synthesize carbamoyl phosphate? | Bicarbonate, Ammonium ion, ATP |
| Which of the following compounds is the precusor of eicosanoids? | Arachidonic acid |
| Which nitrogen atoms of the tetrahydrofolate (THF) molecule can carry one-carbon unit for its transfer to another molecule? | N^5 and/or N^10 |
| Which pathway is involved in the synthesis of leukotrienes? | Lipoxygenase pathway |
| Hyperhomocysteinemia has been linked to cardiovascular and neurological diseases. Deficiency of which of the following compounds increases the levels of homocysteine in the blood circulation? | S-adenosylmethionine (SAM), Tetrahydrofolate (THF), and vitamin B12 |
| Which of the following compounds activates the enzyme phospholipase A2 in order to release the precursor fatty acid for eiconsanoid biosynthesis? | Histamine |
| Which of the following eiconsanoids inhibits platelet aggregation? | Prostacyclin I2 (PGI2) |
| Which of the following intermediates of the Citric Acid Cycle is generated during urea cycle? | Fumarate |
| The following carbon compounds participate in one-carbon group transfer reaction. Which compound is present in its highest oxidation state? | Carbon dioxide |
| Which of the following enzymes is the rate-limiting enzyme in urea biosynthesis? | Mitochondrial carbamoyl phosphate synthetase I |
| If an amino acid is catabolized to produce acetoacetyl-CoA, it is said to be | Ketogenic |
| Which of the following statements best describes the function of glutamate dehydrogenase (GDH) enzyme in amino acid metabolism? | GDH oxidatively deaminates glutamate to produce alpha-ketoglutarate and ammoonium ion |
| Which of the following compounds is required to produce dTMP from dUMP? | N^5, N^10 methylene tetrahydrofolate |
| Which of the following amino acids is the immediate precusor of tyrosine? | Phyneylalanine |
| Tetrahydrofolate (THF) and its derivatives shuffle ___________ between different substrates. | One carbon units |
| Which of the following conditions can produce a negative nitrogen balance in humans? | Kwarshiokor |
| What happens when eicosanoids bind to their selective receptors? | Adenylate cyclase activities are regulated, G proteins pathways are regulated, Protein kinase pathways are regulated, Calcium-dependent pathways are regulated |
| Which of the following functional groups is transferred by S-adenosylmethionine (SAM) to produce epinephrine and norepinephrine? | Methyl group (-CH3) |
| How does aspirin modulates the activity of cyclooxygenase? | By acetylation of the seryl hydroxyl group of the enzyme |
| Which of the following reaction products contributes and incorporates the first nitrogen in urea? | NH4+ ion |
| The disease phenylketonuria is characterized by which of the following? | Phenylalanine is not hydroxylated, Accumulation of phenylpyruvate, High serum levels of phenylalanine, High levels of phenylketone in urine |
| The final product of the urea cycle is urea. Identify the site where urea is finally released immediately after its production. | Cytosol |
| Which of the following compounds is nutritionally essential dietary source of arachidonates in humans? | Linoleate |
| Which of the following cofactors is required for a carboxylation reaction? | Biotin |
| Which of the following amino acids is strictly ketogenic? | Lysine |
| Which of the following is ketogenic? | Leucine |
| In the urea cycle what is the step following the deamination of glutamate to alpha ketoglutarate? | NH4+ + CO2 and 2ATP are combined to form carbamoyl phosphate |
| One carbon groups are transferred between molecules using all of the following except for _____. | B1 |
| What is added as the final step in heme synthesis by heme synthase? | Fe++ |
| True or False? On FH4 a methyl group can be oxidized to a methylene group by a hydration reaction. | False |
| In the urea cycle what is the enzyme required to form citrulline? | Ornithine transcarbamoylase |
| What type of reaction is required to convert oxaloacetate to aspartate? | Transamination |
| Which of the following amino acids synthesized by the human body requires the addition of a sulfur derived ultimately from the essential amino acid methionine? | Cysteine |
| Which of the following is a breakdown product of epinephrine and can provide a methyl group to FH4? | Formaldehyde |
| Purines have single carbon additions added by which of the following during their synthesis? | FH4 |
| What is the enzyme usually bound to PLP in amino transfer reactions? | Transaminase |
| Degradation of which of the following amino acids would yield fumarate? | Aspartate |
| How is the urea cycle regulated? | Feed forward regulation |
| What type of reaction produces the first pyrrole ring (porphobilinogen) in heme synthesis? | Dehydration |
| Which of the following would NOT be a typical symptom of an individual on a chronic high protein diet? | High blood glucose |
| True or False? Decarboxylation of glutamate in the presence of PLP produces the amine g-aminobutyric acid. | True |
| In the salvage of nucleotide bases what is the last step before release to the bloodstream? | Cleavage of the ribose sugar to release the base |
| Which of the following on deamination or aminotransfers produces an alpha ketobutyrate? | Threonine |
| True or False? Glucose can be considered an ultimate source of the one carbon pool by acting through serine. | True |
| Which of the following is required in order for hypozanthine to be converted to zanthine by zanthine oxidase? | Mo++ |
| Which of the following is required in order to convert serine to glycine? | FH4 |
| The addition of a methyl group to dUMP by 5, 10 methylene-FH4 will produce which of the following? | dTMP |
| In the synthesis of the purine nucleotides which of the following is the precursor to the ribose moiety? | 5-Phosphoribosyl-1-pyrophosphate |
| In heme synthesis which of the following condense with glycine to form the beginning structure d-aminolevulinic acid (d-ALA)? | Succinyl CoA |
| True or False? The porphyrin ring of B12 is a flat structure which allows it to act on CH3 in the same fashion that hemoglobin acts on oxygen. | False |
| Which of the following provides the second amine group needed to convert aspartate to asparagine? | Glutamine |
| How many glutamine molecules are used in the synthesis of the purine bases? | 2 |
| Which of the following can NOT be degraded to succinyl CoA? | Alanine |
| True or False? Vitamin B-12 has a flat ring structure called a corin ring incorporated into its matrix. | False |
| In the synthesis of serine the initial reaction that converts 3-phosphoglycerate to 3-phosphohydroxypyruvate is an oxidation reaction requiring which of the following? | NAD+ |
| Which of the following is a byproduct of the usual transamination reaction such as seen in the second reaction in serine synthesis? | Alpha-ketoglutarate |
| Which of the following amino acids is NOT derived from glycolysis? | Arginine |
| Tyrosine can be synthesized by the human body but requires which of the following essential amino acids? | Phenylalanine |
| Which amino acid contributes its nitrogen and two of it's carbons in purine synthesis? | Glycine |
| In the kidney what other amino acid combines with glycine to form guanidinoacetate? | Arginine |
| True or False? Heme synthesis is feedback regulated by heme on heme synthase. | False |
| What is the function of N-acetylglutamate? | Activate carbamoyl phosphate synthetase 1 |
| Which of the following is responsible for the addition of a CO2 group to a receptor molecule? | Biotin |
| In pyrimidine synthesis which of the following is the entire amino acid added to the nucleotide structure? | Aspartate |
| True or False? The only thing SAM does is to add a methyl group to methionine to produce homocysteine. | False |
| Which of the following would NOT be a side chain on a human heme molecule? | Ether |
| Glutamate semialdehyde is the precursor to which of the following amino acids? | Proline |
| The purine base AMP is formed from IMP and which of the following amino acids? | Aspartate |
| Which of the following is the amino acid precursor for SAM? | Methionine |
| What is the enzyme required to release urea from the amino acid arginine? | Arginase |
| In the urea cycle which of the following enzymatic reactions gives off fumarate? | Argininosuccinase |
| How are all of the amino acids deaminated if only glutamate and arginine feed NH4+ into the urea cycle? | The rest of the amino acids have their amino groups transferred to alpha ketoglutamate forming glutamate |
| Which of the following reactions involves vitamin B12 in the transfer of a methyl group? | Movement of a methyl group from methylmalonyl CoA to form succinyl CoA |
| What does the reaction that transfers a methyl group from glycine to FH4 require? | NAD |
| In a transamination reaction how many steps are required to move an amine group from one amino acid to an alpha keto acid forming a second amino acid? | 4 |
Created by:
lesinfl