Heme metabolism

  1. Heme synthesis occurs where in the cell?
    • Mitochondria
    • cytosol
  2. What 3 processes take place in mitochondria and cytosol?
    • Heme synthesis
    • Urea cycle
    • Gluconeogenesis
  3. Acute porphyria usually manisfest how?
    • abdominal pain
    • neuropsychological symptoms
  4. Cutaneous type of porphyria manifests how?
  5. In heme metabolism enzyme deficiency, if a deficiency of enzyme occurs after the formation of porphyrinogen, what types of symtoms are present?
    • cutaneous
    • photosensitivity
    • cutaneous lesions
  6. If an enzyme is deficient before the formation of porphyrinogen, what types of symptoms are present?
    • abdominal pain
    • neurological symptoms
  7. Which porphyrins are of physiological importance?
    Porphyrins III
  8. Lead inhibits which enzyme involved in the synthesis of heme?
    • ALA dehydratase
    • Ferrochelatase
  9. What is the rate determining enzyme in heme synthesis?
    ALA synthase
  10. ALA synthase I is present where?
  11. ALA synthase II is present where?
    Bone Marrow
  12. What are two allosteric inhibitors of ALA synthase?
    • Heme (hemin)
    • Glucose
  13. What inhibits the translation of ALAS 1?
  14. In bone marrow, what controls the synthesis of heme?
    • erythropoietin
    • Intracellular ions
  15. Why would ingestion of drugs stimulate the synthesis of heme in the liver?
    • bc cytochrome p 450 needs heme
    • cyt p 450 is used to metabolize drugs
  16. What is the consequence of irradiating porphyrins?
    they form free radicals
  17. X linked sideroblastic anemia affects which ALA synthase?
    ALAS 2
  18. Which heme synthesis disorders produce cutaneous as well as acute symptoms?
    • Hereditary Coprophyria
    • Variegate Porphyria
Card Set
Heme metabolism
Heme metabolism