Biochemistry LE 6: Amino Acids I (Catabolism of Amino Acids, C Skeleton, and the Urea Cycle)
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Questions and Answers

What is the primary function of amino acids in the body?

  • To synthesize proteins only
  • To generate metabolic energy (correct)
  • To break down larger molecules
  • To synthesize heme and other products

    • What is the major site of catabolic reactions in the human body?

  • The liver (correct)
  • The pancreas
  • The GIT
  • The kidneys

    • How many amino acids are nutritionally essential?

  • 12
  • 20
  • 10
  • 8 (correct)

    • What is the major component of purine and pyrimidine?

    <p>Amino acid</p> Signup and view all the answers

    What is the significance of nutritionally essential amino acids?

    <p>They require a large number of enzymes to biosynthesize</p> Signup and view all the answers

    What occurs in the body when it's in a fed state?

    <p>Anabolism</p> Signup and view all the answers

    What is the process of breaking down larger molecules?

    <p>Catabolism</p> Signup and view all the answers

    Which of the following amino acids is not required in adults?

    <p>Arginine</p> Signup and view all the answers

    What is a positive nitrogen balance accompanied by?

    <p>Growth and pregnancy</p> Signup and view all the answers

    How much dietary protein is taken in per day?

    <p>100 grams</p> Signup and view all the answers

    What is a negative nitrogen balance seen in?

    <p>Surgery, advanced cancer, kwashiorkor, and marasmus</p> Signup and view all the answers

    How much amino acids are produced from protein breakdown and consumed for protein synthesis?

    <p>250-300 grams</p> Signup and view all the answers

    What is BUN a measure of?

    <p>Urea-nitrogen balance</p> Signup and view all the answers

    What is the result of the equilibrium between dietary protein intake and protein synthesis?

    <p>A balance between protein synthesis and protein breakdown</p> Signup and view all the answers

    What is the purpose of amino acids in the body?

    <p>For generating metabolic energy, protein synthesis, and other functions</p> Signup and view all the answers

    When is BUN used to check?

    <p>To check for a hypercatabolic state</p> Signup and view all the answers

    What is the treatment for a hypercatabolic state?

    <p>Giving food supplements and other amino acids</p> Signup and view all the answers

    What is the relationship between dietary protein intake and protein synthesis?

    <p>Dietary protein intake equilibrates with protein synthesis</p> Signup and view all the answers

    What is the main goal of catabolism of amino acids?

    <p>To convert amino acids into energy or storage forms</p> Signup and view all the answers

    Which organ has all the pathways of amino acid synthesis and degradation?

    <p>Liver</p> Signup and view all the answers

    What is the fate of the carbon skeleton of every amino acid?

    <p>Convertible into either carbohydrate or fat or both</p> Signup and view all the answers

    What is the characteristic of ketogenic amino acids?

    <p>They produce ketone bodies</p> Signup and view all the answers

    Which amino acids are solely ketogenic?

    <p>Leucine and Lysine</p> Signup and view all the answers

    What is the characteristic of glucogenic amino acids?

    <p>They can be used for glucose synthesis</p> Signup and view all the answers

    What is the fate of the carbon skeletons of glucogenic amino acids?

    <p>They are degraded to TCA intermediates</p> Signup and view all the answers

    Which amino acids are both ketogenic and glucogenic?

    <p>Isoleucine, Phenylalanine, Tryptophan, and Tyrosine</p> Signup and view all the answers

    What is the relationship between the catabolic and anabolic pathways of amino acid metabolism?

    <p>They have separate regulation</p> Signup and view all the answers

    What is the consequence of impaired intestinal and renal transport of tryptophan in Hartnup disease?

    <p>Pellagra-like symptoms</p> Signup and view all the answers

    Which of the following enzymes is deficient in Classical Type PKU?

    <p>Phenylalanine hydroxylase</p> Signup and view all the answers

    What is the consequence of elevated homocysteine levels?

    <p>Oxidative damage, inflammation, and endothelial dysfunction</p> Signup and view all the answers

    Which amino acid can be synthesized in two pathways?

    <p>Methionine</p> Signup and view all the answers

    What is the role of the Kynurenine-anthranilate pathway in tryptophan metabolism?

    <p>Opens the indole ring that incorporates O2</p> Signup and view all the answers

    What is the effect of folate, Vitamin B12, and B6 on homocysteine levels?

    <p>Decreases homocysteine levels</p> Signup and view all the answers

    What is the consequence of elevated homocysteine levels in pregnant women?

    <p>Increased incidence of neural tube defects</p> Signup and view all the answers

    Which essential amino acid is required to form a nonessential amino acid?

    <p>Methionine</p> Signup and view all the answers

    What is the substrate for the enzyme Hydroxyproline dehydrogenase in the catabolism of 4-hydroxy-L-proline?

    <p>4-hydroxy-L-proline</p> Signup and view all the answers

    What is the primary function of the TDO enzyme in tryptophan metabolism?

    <p>Opens the indole ring that incorporates O2</p> Signup and view all the answers

    What is the product of the nonenzymatic reaction in the catabolism of 4-hydroxy-L-proline?

    <p>γ-hydroxy-L-glutamate-γ-semialdehyde</p> Signup and view all the answers

    What is the purpose of the Expanded Newborn Screening Test?

    <p>To detect early amino acid disorders</p> Signup and view all the answers

    What is one of the most common causes of cardiac arrest in younger patients?

    <p>Maple Syrup Urine Disease (MSUD)</p> Signup and view all the answers

    What is the by-product of DOPA that is important for the brain?

    <p>Tyrosine</p> Signup and view all the answers

    What is the deficiency that can cause Phenylketonuria (PKU)?

    <p>All of the above</p> Signup and view all the answers

    What is the product of the transaminase reaction in the catabolism of 4-hydroxy-L-proline?

    <p>ɑ-ketoγ-hydroxyglutarate</p> Signup and view all the answers

    What is the enzyme involved in the first step of the catabolism of 4-hydroxy-L-proline?

    <p>Hydroxyproline dehydrogenase</p> Signup and view all the answers

    What is the product of the aldolase reaction in the catabolism of 4-hydroxy-L-proline?

    <p>Glyoxylate + pyruvate</p> Signup and view all the answers

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