Iron

Question 1

What are the stable forms of iron?

Answer 1

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

Question 2

Heme is absorbed across the enterocyte brush boarder by what?

Answer 2

heme carrier protein 1 (hcp 1)

Question 3

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

Answer 3

heme oxygenase

Question 4

Nonheme iron is hydrolyzed from food by what enzymes?

Answer 4

proteases and HCL

- mainly into ferric iron (Fe3+)

Question 5

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

Answer 5

divalent metal transporter 1 (DMT 1)

Question 6

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

Answer 6

duodenal cytochrome b (Dcytb) reductase

Question 7

What brush boarder membrane protein facilitates ferric iron absorption?

Answer 7

integrin

Question 8

Integrin facilitates absorption of which form of iron?

Answer 8

oxidized ferric (Fe3+) iron

Question 9

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

Answer 9

Mobilferrin

Question 10

Which amino acids chelate iron?

Answer 10

cysteine and histidine

Question 11

Basolateral boarder transport uses what protein?

Answer 11

ferroportin (FPN 1)

Question 12

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

Answer 12

hephaestin

- contains copper

Question 13

What glycoprotein made in the liver carries 2 iron atoms?

Answer 13

transferrin

Question 14

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

Answer 14

iron

Question 15

What is the bodies iron storage protein?

Answer 15

ferritin

Question 16

What is increased when iron is low?

Answer 16

Dcytb, DMT1, and ferroportin

Question 17

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

Answer 17

hepcidin

Question 18

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

Answer 18

Down regulation of

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

Question 19

The HFE gene is mutated in what genetic disease?

Answer 19

hereditary hemochromatosis

Question 20

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

Answer 20

erythrocyte hemoglobin synthesis

Question 21

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

Answer 21

1. TfR1 - all cell membranes

2. TfR2 - liver and intestines

Question 22

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

Answer 22

transferrin receptors

Question 23

Macrophages can acquire iron by what 3 routes?

Answer 23

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

Question 24

What is the primary storage form of iron?

Answer 24

ferritin

Question 25

What is the long term iron storage protein?

Answer 25

hemosiderin | - degradation product of ferritin

Question 26

What is the control point for iron reg?

Answer 26

liver | - ferritin levels drive hepcidin production

Question 27

What is the function of hepcidin?

Answer 27

suppresses iron absorption

Question 28

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

Answer 28

Iron response element binding protein (IRE-BP)

Question 29

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

Answer 29

aconitase

Question 30

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

Answer 30

mRNA production for ferritin

Question 31

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

Answer 31

ferrochelatase

Question 32

Ferrochelatase is a mito enzyme involved in what?

Answer 32

the last step of heme synthesis

Question 33

What involved in lipid and xenobiotic metabolism also contains iron?

Answer 33

cytochrome P450's

Question 34

NT synthesis requires what 3 monooxygenases?

Answer 34

1. tryptophan hydroxylase 2. phenylalanine hydroxylase 3. tyrosine hydroxylase

Question 35

tryptophan hydroxylase is used for the synthesis of what?

Answer 35

serotonin

Question 36

phenylalanine hydroxylase is used for the synthesis of what?

Answer 36

tryosine

Question 37

tyrosine hydroxylase is used for the synthesis of what?

Answer 37

dopamine

Question 38

Collagen synthesis requires what 2 dioxygenases?

Answer 38

- prolyl hydroxylase | - lysyl hydroxylase

Question 39

Carnitine synthesis requires what 2 dioxygenases?

Answer 39

- trimethyllysine dioxygenase | - 4-butyrobetaine dioxygenase

Question 40

Iron acts as a pro-oxidant through what reaction?

Answer 40

Fenton reaction

Question 41

What vitamin enhances iron absorption?

Answer 41

Vitamin C | - reduces ferric iron to ferrous iron

Question 42

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

Answer 42

copper

Question 43

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

Answer 43

copper

Question 44

How can lead can cause anemia?

Answer 44

ferrochelatase inserts lead into the heme center instead of iron

Question 45

Lead inhibits what zinc dependent enzyme?

Answer 45

delta aminolevulinic acid dehydratase

Question 46

What zinc dependent enzyme is required for heme synthesis?

Answer 46

delta aminolevulinic acid dehydratase

Question 47

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

Answer 47

- selenium | - glutathione peroxidase

Question 48

What is the most common nutritional deficiency world wide?

Answer 48

IRON!!! | 3 billion!

Question 49

What are the 4 susceptible populations to iron dfn?

Answer 49

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

Question 50

Maternal iron dfn is associated with what?

Answer 50

- low birth weight - increases in preterm birth - increases in prenatal mortality

Question 51

The tolerable upper intake level for iron is?

Answer 51

45 mg/day

Question 52

Hereditary hemochromatosis is characterized by what?

Answer 52

increased iron absorption despite high iron stores