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Flashcards in Lecture 38 Deck (21):
1

What is present to shuttle Iron into the cell? What oxidation state can it be in? Is it complete absorption?

- active transport system
- +2 or +3
- no - iron absoprtion isn't very efficient

2

What are some iron transporters and how much iron do they carry?

Ferritin (4500 Fe), Transferrin (2 Fe), Lactoferrin (to get iron into milk)

3

How much iron is in a 70 kg human? Where is it mainly?

- 3-4 g
- hemoglobin or stored ferritin in liver, reticuloendothelial cells and muscle

4

What convert Fe+2 to Fe+3? Why is this important?

- ferroxidases
- in order for RBCs to carry O2, Fe must be +2

5

What is iron deficiency anemia?

- Poorly developed RBCs when FE not available for Hgb synthesis

6

What is Hemochromatosis?

- Excessive Fe absorption and storage leads to liver and other tissue damage

7

What is a heme? Where does synthesis occur?

- A porphyrin ring with Fe
- Synthesis occurs in all tissues, enriched in marrow and liver

8

Heme synthesis begins and ends in what compartment? Where do the intermediate steps occur?

- mitochondria
- cytosol

9

What two compounds combine in the first step of Heme synthesis? What is the enzyme? What inhibits it? What is the cofactor?

- succinyl CoA and glycine
- ALA synthase
- Heme
- Pyridoxal phosphate (a b vitamin)

10

What is the general name for the intermediates occurring in the cytosol during heme synthesis?

- porphorinogen

11

How does the ALA synthase get into the mitochondria? What inhibits transcription of this enzyme?

- a basic signalling sequence is present at its end, a chaperone protein and ATP attach and it gets shuttled in
- heme

12

What happens when 3 H2 are removed from Protoporphyrinogen IX to make Protoporphyrin IX (porphorinogens)?

- more double bonds - double bond structure changes

13

What is a derangement in a number of genes or poryphyrin synthesis called that occur in a number of species called? Dominant or recessive? What happens in case of dominant? What can happen? What do they primarily affect? Where does most heme synthesis occur?

- porphryias
- can be both
- gain of function and overproduction of intermediates
- Defective Hgb and other heme-protein synthesis
- buildup of precursors to blockage point (reddish, brownish, light sensitive)
- nervous system, skin, liver, blood
- liver

14

What does auto-oxidation of Fe2+ in hemoglobin to Fe3+ produce? What color is triple state? What enzyme returns to 2+ state? What is needed for this reaction?

- inactive methemoglobin and superoxide
- brown
- methemoglobin reductase (MR)
- NADH

15

Where is hemoglobin catabolized? What happens to the protein (globin)? What happens to the AA? What happens to Heme?

- reticuloendothelial (RE) cells of spleen and bone marrow
- cleaved off, hydrolyzed, exported as AA
- reused by organism
- degraded and must be excreted (3-5 mg/kg/day)

16

What breaks open Heme ring structure and removes Fe3+? What does it use? What is made? What converts Biliverdin to bilirubin? what does it use? What color is biliverdin? Bilirubin?

- heme oxygenase
- NADPH
- Biliverdin IXa
- biliverdin reductase
- NADPH
- blue-green
- yellow

17

Bilirubin still isn't that soluble - how does body make it so? What enzyme does this? Where primarily? Why is this good?

- glucuronate conjugation
- Bilirubin UDP glucuronyltransferase
- liver
- bilirubin can be excreted via the bile ducts > gi tract > fisces

18

Where does liver take up bilirubin from? Where does it move it? What does it do with it there?

- blood
- smooth ER
- conjugates it, excretes into bile

19

Most of bilirubin is excreted as what? What percentage ends up in periperal blood? What percentage is sent back to liver?

- urobilinogen
- 15%
- 14%

20

Can disorders be measured using conjugated and unconjugated bilirubin in blood? What does elevated conjugated bilirubin mean? Elevated unconjugated?

- yes
- problem in excretion
- problem in transport or conjugation in the liver

21

- What enzyme carries out the second reaction of heme synthesis? where? what inhibits it?

- ALA dehydratase
- cytoplasm
- lead