Iron and Heme

Question 1

What two molecules can iron be bound to during storage?

Answer 1

hemosiderin and ferritin

Question 2

What is the protein that transports iron in the blood?

Answer 2

transferrin

Question 3

What part of the GI tract is iron absorbed in?

Answer 3

duodenum

Question 4

What enzyme in the GI tract can reduce iron from Fe3+ to Fe2+?

Answer 4

Cyt p450

Question 5

What GI protein is responsible for releasing iron into the plasma?

Answer 5

Ferroportin

Question 6

Which protein inhibits ferroportin?

Answer 6

hepcidin

Question 7

What protein transports iron out of the endosome and into the cell?

Answer 7

DMT1

Question 8

What protein does ferritin form when it misfolds and degenerates?

Answer 8

hemosiderin

Question 9

At what level is ferritin production regulated?

Answer 9

post-transcriptional

Question 10

Do iron regulatory proteins bind to the 5’ UTR of ferritin in the presence of absence of iron?

Answer 10

absence

Question 11

What does the presence of iron do to the IRPs?

Answer 11

inhibits their inhibition of iron processing

Question 12

What does free iron do to ALA synthase levels?

Answer 12

increase

Question 13

What does free iron do to transferrin receptor levels?

Answer 13

decreases transferrin receptor levels

Question 14

What percent saturation is transferrin typically?

Answer 14

1/3

Question 15

What is the best measure for serum iron stores?

Answer 15

serum ferritin

Question 16

Which interleukin stimulates the synthesis of hepcidin?

Answer 16

IL-6

Question 17

Absence of what enzyme cause Acute Intermittent Porphyria?

Answer 17

PBG Deaminase

Question 18

Absence of what enzyme causes Porphyria Cutanea Tarda?

Answer 18

UPG Decarboxylase

Question 19

What two enzymes of heme synthesis does lead inhibit?

Answer 19

Ferrochelatase and ALA Dehydratase

Question 20

What organelle is ALA Synthase located? Why?

Answer 20

Mitochondria

availability of succinyl-CoA from citric acid cycle

Question 21

What two enzymes of heme synthesis are located in the mitochondria?

Answer 21

ALA Synthase

Ferrochelatase

Question 22

What is the main inhibitory molecule of ALA synthase?

Answer 22

heme

Question 23

What commonly leads to a porphyria?

Answer 23

alcohol consumption

Question 24

What two products accumulate during Acute Intermittent Porphyria?

Answer 24

ALA and PBG

Question 25

What is more common, AIP or PCT?

Answer 25

PCT

Question 26

How is PCT diagnosed?

Answer 26

urine will fluoresce under UV light

Question 27

What substance accumulates during lead poisoning?

Answer 27

ALA

Question 28

The iron response element is found on what three proteins?

Answer 28

ferritin ALA synthase ferritin receptor

Question 29

What protein can reduce iron on the luminal side of enterocytes?

Answer 29

Cytochrome B

Question 30

What is the oxidation state of iron bound to transferrin?

Answer 30

Fe3+

Question 31

What two locations will iron be stored in during ACD?

Answer 31

RES macrophages enterocytes

Question 32

Hereditary hematochromatosis can be traced back to what gene? increase or decrease?

Answer 32

hepcidin decrease

Question 33

What two products accumulate during AIP?

Answer 33

PBG and ALA

Question 34

What does TIBC specifically measure?

Answer 34

transferrin saturation

Question 35

Transferrin saturation below what percent points to iron deficiency?

Answer 35

15%

Question 36

Is hepcidin expression increased or decreased during hematochromatosis?

Answer 36

decreased

Question 37

What does Fe3+ do to heme synthesis?

Answer 37

repress

Question 38

What does hemin do to heme synthesis?

Answer 38

repress

Question 39

How is AIP diagnosed?

Answer 39

dark red urine

Question 40

Durig iron overload, what is the first cell to express hemosiderin?

Answer 40

macrophages