Block 10 Amino Acid Metabolism

12 Questions | Total Attempts: 1836

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Block 10 Amino Acid Metabolism - Quiz

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Questions and Answers
  • 1. 
    Which of the following amino acids is both essential and glucogenic?
    • A. 

      Alanine (Ala, A)

    • B. 

      Methionine (Met, M)

    • C. 

      Leucine (Leu, L)

    • D. 

      Proline (Pro, P)

    • E. 

      Lysine (Lys, K)

  • 2. 
    K.L. was born in Ville de Saguenay (Quebec), birth was uneventful. However, she failed to thrive. Suddenly at the age of 5 months her condition deteriorated rapidly and she was transferred to an emergency room. Glutamic:pyruvic transaminase (GPT), aspartate aminotransferase (AST), ammonia and creatinine levels in blood were elevated; attending physicians noticed a strong cabbage-like smell originating from her. The most likely diagnosis is
    • A. 

      Tyrosinemia I

    • B. 

      Hyperlysinemia

    • C. 

      Cystinuria

    • D. 

      Methylmalonic aciduria

    • E. 

      Glycine cleavage enzyme deficiency

  • 3. 
    The presence of phenylpyruvate and phenylketones in a child’s blood are indications of the genetic disorder Phenylketonuria.  How does this compound accumulate?  This is a disorder of phenyalanine metabolism which results from:
    • A. 

      Too little product formation of a metabolic pathway

    • B. 

      Too much substrate accumulation for an enzymatic reaction

    • C. 

      An undersupply of tyrosine for protein translation

    • D. 

      An oversupply of homogentisic acid

    • E. 

      Modification of blood proteins by metabolic acids

  • 4. 
    Coconut protein is biologically inferior because it is lacking many essential amino acids. In your efforts to make transgenic coconuts with protein of high biological value, you should definitely ensure that your coconut protein has an adequate amount of:
    • A. 

      Glutamine

    • B. 

      Arginine

    • C. 

      Phenylalanine

    • D. 

      Tyrosine

    • E. 

      Serine

  • 5. 
    High homocysteine levels are associated with an increased risk of atherosclerosis. A deficiency of which of the following enzymes would result in high blood levels of homocysteine (and also methionine)?
    • A. 

      Tyrosine hydroxylase

    • B. 

      Cystathionine synthase

    • C. 

      Threonine dehydratase

    • D. 

      Glutathione reductase

    • E. 

      L-amino acid oxidase

  • 6. 
    . A negative nitrogen balance is most likely in:
    • A. 

      A heavyweight boxer training for the world championship

    • B. 

      A fast-growing teenager who eats 3500 calories of junk food every day

    • C. 

      A political prisoner who went on a hunger strike

    • D. 

      A woman who is 8 months pregnant

    • E. 

      A patient who is recovering from successful cancer surgery and chemotherapy

  • 7. 
    A 2-week-old infant presents with vomiting, lethargy and convulsions without evidence of an infectious process. Laboratory examination reveals hyperammonemia with alkalosis. Glutamine, citrulline and arginine are found elevated in the blood.  The enzyme that is most likely deficient in this patient is:
    • A. 

      Arginase

    • B. 

      Carbamoyl-phosphate synthetase I

    • C. 

      Arginosuccinate lyase

    • D. 

      Ornithine transcarbamoylase

    • E. 

      Arginosuccinate synthetase

  • 8. 
    A newborn with acute encephalopathy is found to have hypoglycemia and ketonuria. Plasma leucine, isoleucine and valine are markedly elevated, but plasma ammonia is normal. This is most likely a case of:
    • A. 

      Ornithine transcarbamoylase deficiency

    • B. 

      Long-chain acyl-CoA dehydrogenase deficiency

    • C. 

      . Methylmalonic acidemia

    • D. 

      Vitamin B12 deficiency

    • E. 

      Maple syrup urine disease

  • 9. 
    A nurse notices that the urine produced by a newborn infant has the odor of maple syrup. Which of the following pathways is most likely defective?
    • A. 

      Metabolism of branched-chain amino acids

    • B. 

      Metabolism of aromatic amino acids

    • C. 

      Metabolism of sulfur-containing amino acids

    • D. 

      Transformation of carbohydrates to amino acids

    • E. 

      One-carbon transfer reactions

  • 10. 
    A 1-year-old child with mental retardation has a deficiency of dihydrobiopterin reductase. This enzyme deficiency leads to an increased blood level of:
    • A. 

      Tyrosine

    • B. 

      Methionine

    • C. 

      Glucocerebroside

    • D. 

      Glycine

    • E. 

      Phenylalanine

  • 11. 
    A.B. is transferred into the emergency room of a local hospital. Upon investigation high levels of glutamate:oxaloacetate transaminase (GOT) and glutamate:pyruvate transaminase (GPT) are found in his serum. His problems probably involve the following organ:
    • A. 

      Heart

    • B. 

      Brain

    • C. 

      Liver

    • D. 

      Muscle

    • E. 

      Lungs

  • 12. 
    The figure shows the metabolism of an anti-hypertensive drug in 258 unrelated British volunteers. Which statement about this experiment is false?
    • A. 

      Patients in group A would get the lowest reduction of blood pressure from a given dose

    • B. 

      Patients in group C would be most at risk of getting an overdose

    • C. 

      The drug is converted by a cytochrome P450

    • D. 

      Patients in the left of the diagram metabolize the drug only very slowly.

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