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MCM > Erythrocyte Biochemistry > Flashcards

Erythrocyte Biochemistry Flashcards

1
Q

How much total body iron is normal?

How much iron is there in hereditary hemochromatosis?

A

3 - 5g

15 g

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2
Q

What is the F8 histidine?

A

Proximal histidine = bound to heme

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3
Q

What does ferritin degrade into?

What is important about this molecule?

A

hemosiderin

It is insoluble, while ferritin is soluble

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4
Q

What is the E7 histidine?

A

distal histidine = O2 binds the iron btw heme and distal histidine (sandwiched btw heme and E7) –> conformational change

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5
Q

What are the 3 parts of folic acid?

A

Pteridine
PABA
glutamate

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6
Q

What causes megaloblastic macrocytic anemia?

A

B12 or folate deficieny –> diminished syntheis of DNA –> large erythrocytes, but not enough of them

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7
Q

What is the other type of adult hemoglobin?

What is it made of?

A

Hb A2 = 3% of hb in body

2 alpha, 2 delta

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8
Q

What does B12 bind to in the stomach?

Where do these come from?

A

R-binders

made by gastric mucosa cells

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9
Q

Where is heme synthesized in a cell?

What makes its uptake there so efficient?

A

mitochondria

Endosome can dock on mitochondria and tranfer iron directly w/out any cytoplasmic proteins

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10
Q

What do you call iron in the blood?

A

transferrin

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11
Q

What side is the basolateral side of the enterocyte?

A

Side touching blood

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12
Q

What is the main adult hemoglobin called?

What is it made of?

A

Hb A

2 alpha and 2 beta chains = tetramer

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13
Q

What carries vitamin B12 through the blood?

A

transcobalamin

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14
Q

What are the two storage forms of iron?

A 
ferritin = soluble
hemosiderin = insoluble
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15
Q

What chromosomes do the genes come from that encode for hemoglobin?

A

16 and 11

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16
Q

What molecule inhibits ferroportin to maintain optimum levels of iron in the blood?

A

Hepcidin –> causes internalization of ferroportin and destruction by proteolysis

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17
Q

What are the embryonic hemoglobins?

A

Gower 1
Gower 2
Portland

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18
Q

What form of iron is found in heme?

A

ferrous = Fe2+

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19
Q

What does myoglobin’s oxygen dissociation curve look like?

What does hemoglobins curve look like?

A

hyperbolic

sigmoidal (due to 2 affinity states)

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20
Q

When the pH drops, what specifically happens to Hb to cause release of O2?

A

His picks up H+ –> conformational change –> release of O2

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21
Q

What causes hypochromic microcytic anemia?

A

iron deficiency

22
Q

What is pernicious anemia?

A

vit B12 deficiency that causes megaloblastic macrocytic anemia
due to lack of intrinsic factor

23
Q

When is the majority of hemoglobin synthesized in RBC production?

A

before extrusion of nucleus

small amount made in reticulocyte

24
Q

Why does fetal Hb have a higher affinity for O2 than maternal Hb

A

HbF does not bind well to 2,3-BPG –> signal to release oxygen isn’t registered, so it keeps O2 more than HbA would

25
Q

How is intrinsic factor-cobalamin taken up?

A

receptor-mediated endocytosis

26
Q

What is being researched now as a potential treatment for sickle cell anemia?

A

induce expression of HbF (fetal hemoglobin)

currently using hydroxyurea (chemotherapy), but trying to find other ways

27
Q

What does ferroxidase do?
What is its other name?
What is its co-factor?

A

Turns Fe2+ into Fe3+ in the blood
ceruloplasmin
Cu

28
Q

Where do you get Vit B12 in your diet?

A

animal products

microorganisms actually make the B12 - no animals can

29
Q

How many heme molecules are in a molecule of hemoglobin?

A

4 = 1 per subunit

30
Q

Where is folic acid absorbed?

A

small intestine (jejunum)

31
Q

What form of iron turns into ferritin for storage?

Where does this occur?

A

Fe3+

in enterocyte

32
Q

When are embryonic hemoglobins “done”?

A

After week 8 of pregnancy

33
Q

What happens to R-binder proteins in the duodenum?

A

Proteases from the pancreas degrade R-binders –> B12 free

34
Q

What subunit of hemoglobin is deformed in sickle cell anemia?

A

beta globin

35
Q

What is hereditary hemochromatosis?

What is the treatment?

A

Iron overload from genetic mutation

blood letting

36
Q

What does ferroportin do?

A

transports Fe2+ (ferrous iron) from enterocyte into blood

37
Q

What makes intrinsic factor?

What does it do and where?

A

Parietal cells make it

Binds B12 after R-binders release it in duodenum –> carries b12 to ileum

38
Q

What form of iron is in Transferrin?

A

Fe3+

I think 2 molecules per transferrin?

39
Q

What is the Bohr Effect?

A

How pH affects O2 affinity:
as pH drops, affinity of Hb for O2 drops too!
How Hb gives tissues O2

40
Q

Which form of folate can give carbons to DNA?

A

methylene

41
Q

Which form of folate do you get “stuck” at?

What do you need to turn it back into THF?

A

methyl

cobalamin (B12)

42
Q

What do you see in the bone marrow in megaloblastic macrocytic anemia?

A

large erythroblasts

also hyper-segmented neutrophils

43
Q

What enzyme converts Fe3+ (from plants) into Fe2+ in the intestinal lumen?
What co enzyme is needed for this?

A

Ferric reductase, otherwise known as duodenal cyt. B

Vitamin C!

44
Q

An increase in what molecule causes Hb to have reduced affinity for O2 in addition to pH lowering?

A

2,3-BPG

45
Q

How much folic acid does the liver store?

How long would this last you?

A

5-10 mg

3-6 months

46
Q

How is transferrin transported into cells for heme synthesis?

A

by receptor-mediated endocytosis via TfR

47
Q

What side is the apical side of the enterocyte?

A

side on intestinal lumen

48
Q

What molecule signals hepcidin synthesis when Tf-Fe binds to its receptor?

A

Hfe (Hephaestin?)

Tf-Fe–> Hfe+Tfr1 complex –>Hfe goes to Tfr2 –>Hepcidin production signalled

49
Q

How do you test for lack of intrinsic factor?

A

Schilling test

50
Q

Where does transferrin end up?

A

liver
spleen
bone marrow

51
Q

What does divalent transporter-1 (DMT1) do?

A

Takes Fe2+ into enterocyte from the intestinal lumen

52
Q

What is the fetal hemoglobin called?

What are its subunits?

A

Hb F

2 alpha, 2 gamma

MCM (14 decks)

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