Erythrocyte Biochemistry - Staudinger Flashcards Preview

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Flashcards in Erythrocyte Biochemistry - Staudinger Deck (25):
1

What are the two variants of adult hemoglobin? What is the fetal variant of hemoglobin? 4

Adult:
α2β2 - 97%
α2δ2 - 3%

Fetal:
α2γ2

2

What is the mutation occurring in sickle cell anemia

Glutamic acid (Glu) --> Val
Negative Neutral
Hydrophilic Hydrophobic

3

What is the effect of 2,3-BPG on hemoglobin

Reduces the O2 affinity for hemoglobin

4

What is positive cooperatively?

Hemoglobin binds O2 in a cooperative fashion. Each binding facilitates the next binding

5

What is the effect of pH on oxygen binding to hemoglobin? 10

Affinity for oxygen decreases with a decrease in pH (oxygen off-loading O2 in high CO2 environments)

6

Why does fetal hemoglobin have such a high affinity for oxygen? 11

2,3-BPG does not bind well to the gamma subunit of hemoglobin therefore oxygen affinity is increased

7

What form is iron stored in the liver as?

Ferritin

8

What form is iron in our diet?

Fe3+ (ferric form)

9

What converts iron from Fe3+ --> Fe2+?

Dcytb (duodenal Cytochrome b)

10

What transports Fe2+ into the enterocyte? 19

DMT1

11

What form of iron does transferrin transport? 20

Fe3+

12

What disease does iron deficiency result in? 22

Hypochromic macrocytic anemia

13

What occurs in hereditary hemochromatosis? 23

An excess of 15g of iron in the blood (normal --> 3-5g)

14

What is the role of hepcidin? 24

When high [Fe2+]
Hepicidin activity high
Ferroportin levels down

When low [Fe2+]
Hepcidin activity low
Ferroportin levels high

15

What is the role of hepcidin? 24

Binds to ferroportin and causes internalization of ferroportin into the enterocyte

16

What cofactors are required for RBC production? 27

Vitamin B12 - cobalamin

Folate

17

What causes megaloblastic anemia? 27

Deficiency of vitamin B12 and Folate

18

What is the first step in folate metabolism? 31

Reduction to THF by dihydrofolate reductase

19

What is the active form of Folate? 32

Tetrahydrofolate --> transfers carbon units from donors to acceptors (DNA syn)

20

What is referred to as a folate trap? 36

Occurs when B12 is not available resulting in folate staying as N5-methyl-THF

21

What does B12 do to N5-methyl-THF (folate)? 37

B12 removes the methyl group making:

THF (also called FH4)
B12-CH3

22

What happens when B12 enters the stomach? 39

B12 is bound by R Binders

Pepsin digests the complex and intrinsic factor binds B12

Intrinsic factor carries B12 to the ileum where receptors bring it into he body

23

What is the purpose of the shilling test? 43

To tell whether a B12 deficiency is due to problems with diet or absorption

24

What is the procedure during the schilling test? 43, 44

If Dietary:
Radioactively labeled cobalmin (B12) ingested, if shows up in urine the problem is dietary

If absorption:
Above procedure will not yield any B12 in the urine

repeat test with radioactively labeled cobalmin AND intrinsic factor

25

What causes Pernicious anemia? 41

Vitamin B12 deficiency due to a lack of intrinsic factor