Erythrocyte Biochemistry Flashcards
What is the first cell in erythropoiesis?
Hemocytoblast (stem cell)
After the hemocytoblast, what is the RBC turned into next
A committed cell which contains packed hemoglobin
At what phase is the nucleus ejected from the normoblast?
The beginning of phase 3
The majority of Hb synthesis is done when
Before the extrusion of the nucleus
What is the structure of hemoglobin
A multi-subunit protein (tetramer) made up of:
2 a-globin chains
2 b-globin chains
Each with a molecule of heme in the center
What is the carrier of O2 in the heme molecule
Fe
Is Heme hydrophobic or hydrophilic
Hydrophobic
What three Hb’s are prevalent in the embryonic phase?
Growler 1
Growler 2
Portland
What Hb is present in the fetal stage of development
Hb F
This starts at wk. 10
What Hb is present in adults
A and A(2)
What two genes encode for Hb
16 and 11
The F8 histidine is also called what and bound to what?
Also called the proximal histidine and bound to heme
The E7 histidine is also called what and what is its function
Also called the distal histidine
It help stabilized the oxygen bound to the heme
What type of curve is noted for myoglobin
Hyperbolic curve
What type of curve is noted for hemoglobin
Sigmoidal
How does oxygen bind to Hb?
In a cooperative manner
This means that the binding of one molecule of oxygen facilitates the binding of the other three
Drop of pH allows for what in the Bohr effect
A decrease in the affinity of bound oxygen which allows for a greater release of oxygen into the cells
What is the general pathway that iron is absorbed into the liver
Gut lumen - intestinal absorption - plasma transferrin ion - liver
Define hereditary hemochromatosis. What is the clinical manifestation
Increased amount of iron in the blood (15g, norm is 3-5)
Presents as organ dysfunction due to iron overload: cirrhosis, arthritis, cardiomyopathy
What protein is involved in iron homeostasis
Hepcidin
What is the function of hepcidin
Binds to Ferroportin which causes the internalization of Ferroportin
When iron is high, what happens
When iron is low what happens
Hepcidin is over expressed, ferroportin levels drop, iron absorption is low
Hepcidin expression is down, ferroportin levels up, iron absorption is high
What cofactors influence RBC production
Cobalamin and folic acid
Deficiency of B12 and folate can cause what
Megalobastic anemia
This us due to diminishing synthesis of DNA
What are the three parts of folate
Pteridine (nitrogen containing ring)
P-amino-benzoic-acid ring (PABA
Glutamate residue chain
What is the active form of folate
Tetrahydrofolate (THF)
Where is folate absorbed
In the jejunum
What happens with a Cobalamin deficiency
Pernicious anemia
This is a megaloblastic macrocytic anemia
