[MCQs] Lipid, Amino Acid, Nucleotide, and Nitrogen Metabolism Quiz – Part 2 (18 test – end)

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Part 1 (20 test) | Part 2 (18 test – end)  

1. Which of the following transamination reactions produces an intermediate that will directly facilitate oxidative phosphorylation as well as gluconeogenesis?

1. Asparagine to aspartate to oxaloacetate
2. Cystine to cysteine
3. Lysine to glutaryl-CoA
4. Serine to glycine
5. Methionine to cystine

2. Which of the following is not used in the synthesis of fatty acids?

1. ATP
2. Cobalamin (vitamin B12)
3. FADH2
4. HCO3–
5. NADPH

3. Which of the diagrammatic structures below models the configuration of lipids emulsified prior to hydrolysis during digestion?

1. Structure A
2. Structure B
3. Structure C
4. Structure D
5. Structure E

4. A 36-hour-old African American boy is evaluated because of inability to breast-feed and found to have severe hypotonia (low muscle tone). The child lays in a frog leg posture with minimal spontaneous movements, and the head and legs dangle to the bed when suspended by his stomach. A large anterior fontanel is noted, and initial laboratory tests indicate elevated liver The physician suspects Zellweger syndrome (MIM*214100), an end phenotype reflecting peroxisome dysfunction that may be caused by mutations in several different peroxisomal membrane protein genes. The diagnosis is confirmed by demonstrating elevated plasma levels of very long chain fatty acids and of erythrocyte plasmalogens. Which of the following compounds is the starting point of ether lipid and plasmalogen synthesis?

1. Acetyl-CoA
2. Pyruvate
3. Dihydroxyacetone phosphate
4. Malonyl-CoA
5. Palmitoyl-CoA

5. A 5-year-old Caucasian girl presents to the emergency room for evaluation of respiratory distress. She has seemed tired for the past week in that she does not play after school and goes to bed without prompting. The presiding physician obtains a basic metabolic panel that shows glucose of 250 mg/dL (normal 70-100) and a pH of 7.1. Urinalysis using a standard reagent strip is negative for nitrites and white blood cells that indicate infection but is strongly positive for the presence of ketones. The physician concludes that the child has likely diabetic ketoacidosis and that the respiratory distress is due to Kussmaul breathing—reflexive deep respirations that attempt to compensate for the acidosis by lowering carbon Which of the following are “ketone bodies” that registered positive on the urine reagent strip for ketones in this  child?

1. Acetone and ethanol
2. β-Hydroxybutyrate and acetoacetate
3. Pyruvate and lactate
4. Fumarate and succinate
5. Oxaloacetate and pyruvate

6. Gangliosides and receptors for hormones such as glucagon can be found in which of the following structures?

1. Plasma membrane
2. Mitochondria
3. Lysosomes
4. Endoplasmic reticulum
5. Ribosomes

7. Which of the following is the major source of extracellular cholesterol for human tissues?

1. Very low density lipoproteins  (VLDLs)
2. Low-density  lipoproteins (LDLs)
3. High-density  lipoproteins (HDLs)
4. Albumin
5. γ-Globulin

8. Which amino acid can be converted to an intermediate of the citric acid cycle and can be directly converted to urea?

1. Ornithine
2. Lysine
3. Arginine
4. Glutamate
5. Tyrosine

9. When the liver is actively synthesizing fatty acids, a concomitant decrease in β-oxidation of fatty acids is due to which of the following?

1. Inhibition of a translocation between cellular compartments
2. Inhibition by an end product
3. Activation of an enzyme
4. Detergent effects
5. Decreases in adipocyte lipolysis

10. A 4-year-old African American girl presents in the clinic with megaloblastic anemia (fewer red blood cells that are larger than normal) and failure to Blood chemistries reveal orotic aciduria (MIM*258900). Enzyme measurements of white blood cells reveal a deficiency of the pyrimidine biosynthesis enzyme orotate phosphoribosyltransferase and abnormally high activity of the enzyme aspartate transcarbamoylase. Which of the following treatments will reverse all symptoms if carried out chronically?

1. Blood transfusion
2. White blood cell transfusion
3. Dietary  supplements of phosphoribosylpyrophosphate (PRPP)
4. Oral thymidine
5. Oral uridine

11. A 1-year-old Hispanic boy has a normal birth and infantile history except for delay in sitting up, crawling, and standing (delayed motor milestones). He begins the unusual habit of chewing on his fingers and lips and, in one instance, bites through the lip and leaves a large His physician documents an elevated serum uric acid and suspects Lesch-Nyhan syndrome (MIM*300322). In considering potential therapy, the physician reads that purines are overproduced in gout and Lesch- Nyhan syndrome, causing hyperuricemia, yet the hypoxanthine analog allopurinol is only effective in gout. Allopurinol does not treat the neurologic symptoms of Lesch-Nyhan syndrome because it does not do which of the following?

1. Decrease de novo purine synthesis
2. Decrease de novo pyrimidine synthesis
3. Diminish urate synthesis
4. Increase phosphoribosylpyrophosphate (PRPP) levels
5. Inhibit xanthine oxidase

12. Which of the following would make hyperuricemia very unlikely in a patient?

1. Lesch-Nyhan syndrome
2. Gout
3. Xanthine oxidase hyperactivity
4. Carbamoyl phosphate synthase deficiency
5. Purine overproduction secondary to von Gierke disease

13. A 35-year-old Caucasian male presents to the emergency room with an acute abdomen (severe abdominal pain with tightness of muscles, decreased bowel sounds, and vomiting and/or diarrhea). He has been drinking, and a urine sample is unusual because it has a port-wine Past history indicates several prior evaluations for abdominal pain, including an appendectomy. The physician notes unusual neurologic symptoms with partial paralysis of his arms and legs. At first concerned about food poisons such as botulism, the physician recalls that acute intermittent porphyria may cause these symptoms (MIM*176000) and consults a gastroenterologist. Elevation of which of the following urinary metabolites would support a diagnosis of porphyria?

1. Urobilinogen and bilirubin
2. Delta-aminolevulinic acid and porphobilinogen
3. Biliverdin and stercobilin
4. Urobilin and urobilinogen
5. Delta-aminolevulinic acid and urobilinogen

14. Hyperuricemia in Lesch-Nyhan syndrome is due to a defect in which of the following pathways?

1. Purine biosynthesis
2. Pyrimidine biosynthesis
3. Purine salvage
4. Pyrimidine salvage
5. Urea cycle

15. Which of the following is the rate-controlling step of pyrimidine synthesis that exhibits allosteric inhibition by cytidine triphosphate (CTP)?

1. Aspartate transcarbamoylase
2. Hypoxanthine-guanine phosphoribosyl transferase (HGPRT)
3. Thymidylate synthase
4. Ribose-phosphate pyrophosphokinase
5. Xanthine oxidase

16. Which of the following compounds is a required substrate for purine biosynthesis?

1. 5-Methyl thymidine
2. Ara C
3. Ribose phosphate
4. 5-Phosphoribosylpyrophosphate (PRPP)
5. 5-FU

17. Which of the following compounds is joined with nicotinamide to form NAD and NADP, components that are deficient in niacin deficiency?

1. Cytosine monophosphate
2. Inosine diphosphate
3. Thymidine monophosphate
4. Hypoxanthine monophosphate
5. Adenosine diphosphate

18. A hitherto unknown disease is suggested by a 28-year-old male who has reducing substances in his urine, mild liver disease, and decreased liver glycogen upon liver Which of the following metabolites would be the best candidate for measurement as a clue to the cause of disease?

1. Glucose 1-phosphate
2. Fructose 6-phosphate
3. Fructose 1,6-bisphosphate
4. Cytosine diphosphate
5. Uridine diphosphate