Erythrocyte Biochemistry Flashcards
Which of the following subunits make up fetal hemoglobin?
A. alpha2-beta2
B. alpha2-gamma2
C. gamma2-beta2
D. alpha2-alpha2
alpha2-gamma2
Which of the following correctly describes the conformation change of Hb upon O2 binfing to the heme iron?
A. Hb decreases affinity for O2
B. The proximal histidine and distal histidine both pull down the globin chain
C. The distal histidine helps stabilze the O2
D. The proximal histidine moves up and and releases its interaction with the globin chain
The distal histidine helps stabilze the O2
Which of the following correctly describes the effect of pH on O2 binding affinity of Hb?
A. Hb increases affinity for O2
B. Left Shift seen on O2 dissociation curve
C. Hb decreases affinity for O2
D. None of the above
Hb decreases affinity for O2
This is also seen in: increase 2,3-BPG, exercise or sickle cell anemia
Why does HbF binds O2 better than HbA?
HbF does not bind 2,3-BPG well
A third of our iron is stored in what 3 locations of our body?
Liver
Spleen
Bone Marrow
Which of the following is able to bind Ferric Iron (Fe3)?
A. Hepcidin
B. Ferroportin
C. Feroxidase
D. Ferritin
Ferritin
______ exports ferrous iron (Fe2) out of the cells and requires _________ to function. The exporting protein however is destroyed/regulated by ________
Ferroportin exports ferrous iron (Fe2) out of the cells and requires Hephaestin to function. The exporting protein however is destroyed/regulated by Hepcidin
Which of the following is correct about the transport of iron in the blood?
A. Transferrin binds and transports Fe2
B. Transferrin binds and transports Ferrous
C. Hepcidin binds and transports ferric
D. Transferrin binds and transports Fe3
Transferrin binds and transports Fe3
Which of the following is responsible for oxidizing animal product derived Ferrous to Ferric to be stored in Ferritin?
A. DMT-1 (Divalent Transporter)
B. Feroxidase/Cerruloplasmin
C. Feric Reductase
D. Duodenal Cytochrome-like B protein
E. C and D
F. A and B
Ferroxidase aka Cerruloplasmin
Which of the following is responsible for reducing Ferric to Ferrous in the presence of Vitamin C?
A. DMT-1 (Divalent Transporter)
B. Feroxidase/Cerruloplasmin
C. Feric Reductase
D. Duodenal Cytochrome-like B protein
E. C and D
F. A and B
C and D
Ferric Reductase
Duodenal Cytochrome-like B protein (dcytb)
Which of the following correctly expresses how transferrin is removed?
A. Combustion via an oxidation reaction
B. REceptor mediated endocytosis and internalized via COP2 coated puts into endosomes
C. TfR enodocytoses transferrin into clathrin coated pits
D. None of the above
TfR enodocytoses transferrin into clathrin coated pits
Which of the following regulates the expression of Hepcidin in the liver?
A. Human Homeostatic Iron Regulator Protein that is initiated irrespective of iron levels
B. HFE that is responsive to iron levels
C. Presence of Hemosiderin
D. None of the above
HFE that is responsive to iron levels
When iron levels are low which of the following is most likely to be occuring?
A. Hepcidin expression: decreases, Ferroportin: increases, Iron Absorption: increases
B. Hepcidin expression: increases , Ferroportin: decreases , Iron Absorption: decreases
C. Hepcidin expression: decreases , Ferroportin: increases , Iron Absorption: decreases
D. Hepcidin expression: decreases , Ferroportin: decreases , Iron Absorption: decreases
A. Hepcidin expression: decreases, Ferroportin: increases, Iron Absorption: increases
Which of the following is the correct clinical presentation of Hereditary Hemochromatosis?
A. IRon absorption decreases in heart, liver, and pancreas begin to fail
B. Iron absorption increases and accumulates in the bone marrow, heart, and spleen
C. Iron absorption increases and accumulates in the heart, liver, and pancreas
D. None of the above
Iron absorption increases and accumulates in the heart, liver, and pancreas
NOTE: HH is iron overload
RBC production is dependent on what two substances, who’s absence would lead to Megaloblastic anemia?
Folate (folic acid)
B12 (cobalamin)
Which of the following is the active form of folate, which is important for DNA synthesis due to its involvement with synthesis of purines and pyrimidine thymine?
A. THF
B. DHF
C. BHF
D. All of the above are considered active forms
THF
What is the effect of methotrexate in folate synthesis?
A. Failure to absorb Folic Acid in the small intestines (jejunum)
B. Irradication fo Bqw
C. Inhibition of DHF reductase leading
D. None of the above
Inhibition of DHF reductase leading
A deficiency in vitamin B12 can result from lack of intrinsic factor. BEcause of this we can develop a folate trap where we would most liekly see the buildup of which of the following?
A. FH4
B. DHB
C. N5-methyl THF
D. All of the above
N5-methyl THF
FH4 is what we wouldn’t be able to make, or at least would have very low levels of
Which of the following substances is made in the stomach and carries B12 to the ileum where it’s released into the blood stream?
A. R-binding protein
B. Intrinsic Factor
C. Transcobalamine II
D. Methotrexate
Intrinsic Factor
Which of the following substances carries B12 complex until its taken up into the cells?
A. R-binding protein
B. Intrinsic Factor
C. Transcobalamine II
D. Methotrexate
Transcobalamine II
T/F: When performing a Schilling Test, if radiolabeled B12 is not present in the urine then we test again with intrinsic factor present
True
Heme Biosynthesis happens primarily in the liver and erythroid cells of the bone marrow. It occurs in three steps. Name those 3 steps and the enzymes involved
- Generation of ALA w/ ALA synthase
- Generation of Coproporphyrinogen III w/ PBG deaminase
- Generation of Protoporphyrin and introduction of iron
w/ Protoporphyrinogen Oxidase
(All Cop Prototype APP)
ALA synthase involved in forming ALA from succinyl coA and glycine requires which of the following substrates or RBCs will present as pale?
A. B12
B. Niacin
C. Vitamin C
D. B6 (pyridocal phosphate)
B6 (pyridocal phosphate)
Lead poisoning lowers heme production by inactivating which of the following enzymes?
A. Protophyrinogen Oxidase and ALA dehydrogenase
B. PBG deaminase and Ferrochelatase
C. ALA dehydrogenase and Ferrochelatase
D. PBG demanisae and PRotophyrinogen Oxidase
ALA dehydrogenase and Ferrochelatase
NOTE: this causes build up of both ALA and protoporphyrin IX, and ALA is neurotoxic
Which of the following poryphrias is caused by PBG demaniase mutation, and results in symptoms of abdominal pain and neurological dysfunction?
A. Acute Intermittent Poryphyria
B. Congenital Erythropoietic Porphyria
C. Porphyria Cutanea Tarda
D. Variegate Porphyria
Acute Intermittent Poryphyria
Which of the following poryphrias is caused by Uroporphyrinogen III synthase is effected in erythrocytes, and results in photosensitivity and red colored urine and teeth?
A. Acute Intermittent Poryphyria
B. Congenital Erythropoietic Porphyria
C. Porphyria Cutanea Tarda
D. Variegate Porphyria
Congenital Erythopoietic Poyphyria
Which of the following poryphrias would you see an accumulation of uroporyphrinogen 3 leading to red wine colored urine, that’s caused by a defect in uropophyrinogen decarboxylase?
A. Acute Intermittent Poryphyria
B. Congenital Erythropoietic Porphyria
C. Porphyria Cutanea Tarda
D. Variegate Porphyria
Porphyria Cutanea Tarda
NOTE: it’s the most common in the US
Which of the following poryphrias is caused by a defect protoporphrinogen IX oxidase? What is another name for this porphyrias?
A. Acute Intermittent Poryphyria
B. Congenital Erythropoietic Porphyria
C. Porphyria Cutanea Tarda
D. Variegate Porphyria
Variegate Porphyria
Celebrity Poryphyria
The heme degredation is handled by reticulo-endothelial system, that degrades hemoglobin into globin (becomes AA) and heme (processed for degredation).
Cool
Which of the following enzymes can remove the bridge between the pyrrole rings of heme?
A. Biliverdin Reductase
B. Heme Oxygenase
C. Heme oxygenase with O2
B. UDP-glucoronyl transferase
Heme oxygenase with O2
Which of the following enzymes reduces biliverdin to bilirubin?
A. Biliverdin Reductase
B. Bilirubin Synthase
C. Heme oxygenase with O2
B. UDP-glucoronyl transferase
Biliverdin Reductase
Free/unconjugated/indirect bilirubin is insoluble and converted to its conjugated form in which of the following scenarios?
A. Liver UDP-glucoronyl transferase
B. Spleen UDP-glucoronyl reductase
C. Liver UDP-glucoronyl reducatase
D. None of the above
Liver UDP-glucoronyl transferase
Correclty label the type of jaundice that is described below:
- Increased production of unconjugated BR
- Impaired hepatic uptake, conjugation, or secretion of conjugated BR as seen in Criggler Najjar syndrome and Gilbert Syndrome
- Problems with bilirubin secretion where we see dark urine
- Prehepatic Jaundice: Increased production of unconjugated BR
- Intrahepatic Jaundice: Impaired hepatic uptake, conjugation, or secretion of conjugated BR as seen in Criggler Najjar syndrome and Gilbert Syndrome
- Post-hepatic JaundiceProblems with bilirubin secretion where we see dark urine
What is the difference between Cirggler Najjar Syndrome I vs II in neonatal jaundice
Type I the UDP-GT enzyme is absent, while in Type II the UDP-GT enzyme is impaired and less active
T/F: in hepatitis you see elevated levels of unconjugated and conjugated BR in the blood , with a dark tea colored urine
True
