Amino acid metabolism

    Cards (24)

    • What is the main focus of amino acid metabolism?
      Degradation of amino acids from proteins
    • Why are amino acids risky to accumulate in the body?
      They have key functions and regulate metabolism
    • Where does excess amino acid degradation primarily occur?
      Liver
    • What is protein turnover?
      Regulated degradation and synthesis of proteins
    • What happens to damaged proteins in the body?
      They are removed
    • How is ammonia formed in the body?
      Through amino acid breakdown
    • Why is ammonium ion (NH4+) considered toxic?
      It leads to severe neurological problems
    • What is the major nitrogen-containing excretory molecule?
      Urea
    • What percentage of nitrogen excretion is in the form of urea?
      80%
    • What are the three steps in the synthesis of urea?
      Transamination, deamination, urea cycle
    • What role do aminotransferases play in amino acid metabolism?
      They move amino groups between amino acids
    • What is the function of glutamine synthase?
      Adds NH4+ to glutamate to form glutamine
    • What are the major carriers of nitrogen in the blood to the liver?
      Alanine and glutamine
    • Where does deamination occur?
      In the liver
    • What is generated as an end-product of the urea cycle?
      Fumarate
    • How is fumarate converted for transport back to the mitochondrial matrix?
      Converted to malate via malate-aspartate shuttle
    • What happens to carbon skeletons after amino acid degradation?
      Converted into major metabolic intermediates
    • What are ketogenic amino acids degraded to?
      Acetyl-CoA or acetoacetyl-CoA
    • What can glucogenic amino acids be converted into?
      Pyruvate or TCA cycle intermediates
    • What are the inherited disorders of amino acid degradation?
      • Alcaptonuria: Blocked degradation of phenylalanine and tyrosine
      • Maple syrup urine disease: Blocked degradation of valine, isoleucine, and leucine
      • Phenylketonuria: Accumulation of phenylalanine leads to mental retardation
    • What is the consequence of a defect in a urea cycle enzyme?
      Accumulation of urea cycle intermediates
    • What happens to glutamine levels in the circulation with urea cycle disorders?
      Glutamine levels increase
    • What happens to α-ketoglutarate levels in urea cycle disorders?
      They become too low to fix ammonium
    • What is the effect of elevated ammonia levels in the blood?
      They are toxic for the nervous system
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