Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
MBC - Lecture 44
Heme Biosynthesis (Douglas)
| Question | Answer |
|---|---|
| Lecture 44 | Heme Biosynthesis |
| ___ is the most common porphyrin in the body. | Heme |
| Heme is complexed with ___, ___, and ___. | hemoglobin, myoglobin, and cytochromes |
| Heme transports ___. | oxygen |
| Heme is degraded and excreted in the gut and urine as a conjugate of ___. | bilirubin |
| Glycine + Succinyl-CoA → ___ | 5-aminolevulinate (5-ALA)/ δ -aminolevulinate |
| 5-ALA goes through 7 enzymatic steps to produce ___. | heme |
| δ- aminolevulinate synthase (ALAS) contains ___. | pyridoxal phosphate (PLP) |
| Lead inactivates the following enzymes: | δ-aminolevulinic acid dehyrdatase, protoporphyinogen oxidase, and ferrochelatase |
| Uroporphyrinogen decarboxylase acts on side chains of ___. | uroporphyinogen |
| Deficiency of uroporphyrinogen decarboxylase leads to accumulation of ___. | uroporphyrinogen III |
| ___ inhibits uroporphyrinogen decarboxylase. | Iron salts |
| Poryphria Cutenea Tarda | Most common porphyria, light sensitivity, recessive allele leading to 50% reduction of uroporphyrinogen decarboxylase activity with normal hepatic heme production, makes carrier sensitive to alcohol |
| Heme biosynthesis begins and ends in the ___. | mitochondria |
| Aminolevulinate Synthase (ALAS) | Catalyzes formation of 5-aminolevulinate (ALA) in the mitochondria from glycine and succinyl-CoA |
| Aminolevulinate Dehydratase (ALAD) | Catalyzes formation of porphobilinogen (PBG) in the cytoplasm from ALA (aka porphobilinogen synthase) |
| Ferrochelatase | Catalyzes formation of heme in the mitochondria by addition of Fe2+ to protoporphyrin |
| Under conditions of low iron availability, ___ can be inserted, resulting in a fluorescent molecule. | zinc |
| ___ is a negative feedback inhibitor of 5-ALAS. | Heme |
| 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) inhibits ___. | ferrochelatase |
| Porphyria | Partial interruption in heme synthesis leading to excess porphyrin precursors in the liver |
| ___ and ___ are neurotoxins, measurable in urine. | ALA and porphobilinogen |
| Symptoms of porphyria include: | abdominal pain, peripheral neuropathies, respiratory paralysis, and acute psychotic episodes |
| Porphyria are often ___, but can be triggered by fasting, dieting, or a chemical/hormone/drug. | asymptomatic |
| Heme is degraded to non-soluble ___. | bilirubin |
| Heme is cleaved by ___ to form biliverdin. | heme oxygenase |
| Biliverdin is reduced by ___ to form bilirubin. | biliverdin reductase |
| Bilirubin is transported to the __ by conjugation with ___. | liver, albumin |
| Conjugation of bilirubin and ___, making it soluble for excretion in bile. | glucuronic acid |
| Glucuronyl Bilirubin Transferase | Catalyzes conjugation of bilirubin with glucuronic acid to form bilirubin diglucuronide |
| Bilirubin diglucuronide is released to the intestine and degraded to ___. | urobilinogen |
| 75% of bilirubin is from ___. | red blood cells (250-350 mg/day) |
| Majority is excreted in feces as ___. | stercobilin (brown color) |
| Normal bilirubin levels are <___ micromoles per liter. | <17 |
| Jaundice is clinically obvious when bilirubin levels are >___ micromoles per liter. | >50 |
| Pre-Hepatic Jaundice | Increased bilirubin production by RBC breakage, blood extravasation, sickle cell anemia |
| Intrahepatic Jaundice | Inability for liver to uptake, conjugate, or secrete bilirubin |
| Post-Hepatic Jaundice | Obstruction of biliary excretion |
| Hepatic Failure | Acetaminophen toxicity, 70 micromolar bilirubin |
| Neonatal Jaundice | Common 48 hours after birth, after 10 days is abnormal, 150 micromolar bilirubin |
| Obstructive Liver Disease | 230 micromolar bilirubin |
| ___ measured in blood as markers for liver function/damage. | Transaminases |
Created by:
emyang
Popular Chemistry sets