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Nutritional Bio 1 - Ca-Zn > Iron > Flashcards

Iron Flashcards

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1
Q

What are the stable forms of iron?

A

oxidized ferric (Fe3+) iron and reduced ferrous (Fe2+) iron

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2
Q

Heme is absorbed across the enterocyte brush boarder by what?

A

heme carrier protein 1 (hcp 1)

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3
Q

What enzyme hydrolyzes heme into ferrous iron (Fe2+) and protoporphyrin?

A

heme oxygenase

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4
Q

Nonheme iron is hydrolyzed from food by what enzymes?

A

proteases and HCL

- mainly into ferric iron (Fe3+)

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5
Q

Ferrous (Fe2+) is absorbed across the brush boarder by what?

A

divalent metal transporter 1 (DMT 1)

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6
Q

What enzyme reduces oxidized ferric (Fe3+) iron to reduced ferrous (Fe2+) iron?

A

duodenal cytochrome b (Dcytb) reductase

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7
Q

What brush boarder membrane protein facilitates ferric iron absorption?

A

integrin

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8
Q

Integrin facilitates absorption of which form of iron?

A

oxidized ferric (Fe3+) iron

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9
Q

Iron, calcium, zinc, and copper are transported around the cell by what protein?

A

Mobilferrin

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10
Q

Which amino acids chelate iron?

A

cysteine and histidine

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11
Q

Basolateral boarder transport uses what protein?

A

ferroportin (FPN 1)

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12
Q

Ferrous iron is transported across the basolateral boarder by what protein?

A

hephaestin

- contains copper

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13
Q

What glycoprotein made in the liver carries 2 iron atoms?

A

transferrin

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14
Q

A copper deficiency could potentially lead to what other mineral deficiency?

A

iron

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15
Q

What is the bodies iron storage protein?

A

ferritin

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16
Q

What is increased when iron is low?

A

Dcytb, DMT1, and ferroportin

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17
Q

When iron stores in the liver are high, the liver secretes what hormone?

A

hepcidin

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18
Q

Hepcidin reduces iron absorption at the brush boarder by what 3 mechanism?

A

Down regulation of

1. DMT1 and hcp 1
2. reducing proteins like Dcytb
3. ferroportin (FPN1) transports
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19
Q

The HFE gene is mutated in what genetic disease?

A

hereditary hemochromatosis

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20
Q

Transferrin delivers 80 % of the iron to bone marrow for what function?

A

erythrocyte hemoglobin synthesis

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21
Q

What are the 2 isoforms of transferrin receptors and where are they found?

A
  1. TfR1 - all cell membranes

2. TfR2 - liver and intestines

22
Q

What can be used as a clinical indicator of an iron dfn?

A

transferrin receptors

23
Q

Macrophages can acquire iron by what 3 routes?

A
  1. phagocytosis of RBC’s
  2. receptor mediated endocytosis of hemoglobin
  3. receptor mediated endocytosis of transferrin
24
Q

What is the primary storage form of iron?

A

ferritin

25
Q

What is the long term iron storage protein?

A

hemosiderin

- degradation product of ferritin

26
Q

What is the control point for iron reg?

A

liver

- ferritin levels drive hepcidin production

27
Q

What is the function of hepcidin?

A

suppresses iron absorption

28
Q

When iron concentrations are high, which protein is fully saturated with 4 iron molecules?

A

Iron response element binding protein (IRE-BP)

29
Q

Once IRE-BP is fully saturated it binds to what cytosolic enzyme?

A

aconitase

30
Q

When IRE-BP is bound to aconitase, what is prevented?

A

mRNA production for ferritin

31
Q

What mitochondrial enzyme is involved in the last step of heme synthesis wherein iron is incorporated into the protoporphyrin ring?

A

ferrochelatase

32
Q

Ferrochelatase is a mito enzyme involved in what?

A

the last step of heme synthesis

33
Q

What involved in lipid and xenobiotic metabolism also contains iron?

A

cytochrome P450’s

34
Q

NT synthesis requires what 3 monooxygenases?

A
  1. tryptophan hydroxylase
  2. phenylalanine hydroxylase
  3. tyrosine hydroxylase
35
Q

tryptophan hydroxylase is used for the synthesis of what?

A

serotonin

36
Q

phenylalanine hydroxylase is used for the synthesis of what?

A

tryosine

37
Q

tyrosine hydroxylase is used for the synthesis of what?

A

dopamine

38
Q

Collagen synthesis requires what 2 dioxygenases?

A
  • prolyl hydroxylase

- lysyl hydroxylase

39
Q

Carnitine synthesis requires what 2 dioxygenases?

A
  • trimethyllysine dioxygenase

- 4-butyrobetaine dioxygenase

40
Q

Iron acts as a pro-oxidant through what reaction?

A

Fenton reaction

41
Q

What vitamin enhances iron absorption?

A

Vitamin C

- reduces ferric iron to ferrous iron

42
Q

What is the cofactor for the ferroxidase enzymes hephaestin and ceruloplasmin?

A

copper

43
Q

What mineral is needed to mobilize iron out of the small intestine?

A

copper

44
Q

How can lead can cause anemia?

A

ferrochelatase inserts lead into the heme center instead of iron

45
Q

Lead inhibits what zinc dependent enzyme?

A

delta aminolevulinic acid dehydratase

46
Q

What zinc dependent enzyme is required for heme synthesis?

A

delta aminolevulinic acid dehydratase

47
Q

Iron deficiency is associated with reductions in what mineral and what enzyme?

A
  • selenium

- glutathione peroxidase

48
Q

What is the most common nutritional deficiency world wide?

A

IRON!!!

3 billion!

49
Q

What are the 4 susceptible populations to iron dfn?

A
  1. infants/young children
  2. adolescents (growth spurts)
  3. females during childbearing years
  4. pregnant women
50
Q

Maternal iron dfn is associated with what?

A
  • low birth weight
  • increases in preterm birth
  • increases in prenatal mortality
51
Q

The tolerable upper intake level for iron is?

A

45 mg/day

52
Q

Hereditary hemochromatosis is characterized by what?

A

increased iron absorption despite high iron stores

Nutritional Bio 1 - Ca-Zn (5 decks)

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