Biochemistry- Hemoglobins Flashcards

1
Q

What substance, when bound to heme, weakens the oxygen/heme bond causing the oxygen to be released?

A

2,3- diphosphoglycerate

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2
Q

What can bind to hemoglobin?

A

O2, CO2, CO, H+, and 2,3- diphosphoglycerate

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3
Q

What are the 3 functions of hemoglobin?

A

oxygen transport, CO2 transport, blood buffer

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4
Q

What 2 substances are the starting material for heme synthesis?

A

succinyl CoA, glycine

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5
Q

What do succinyl CoA and glycine form?

A

delta aminolevulenic acid (and then –> heme formation)

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6
Q

What is the regulatory enzyme in heme synthesis?

A

Delta aminolevulenic acid synthase (ALAS)

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7
Q

The formation of porphobilinogen from Delta aminolevulenic acid is catalyzed by what enzyme?

A

Delta aminolevulenic dehydrogenase (ALAD)

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8
Q

What substance inhibits ALAD?

A

Lead

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9
Q

What mineral is incorporated into heme?

A

Iron

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10
Q

Where does heme synthesis take place?

A

mitochondria

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11
Q

Where in the body does heme synthesis take place?

A

bone marrow

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12
Q

Congenital deficiencies of certain enzymes in the heme synthesis are known as:

A

porphyrias

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13
Q

In what other substances is heme found?

A

Myoglobin, cytochromes

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14
Q

Where does catabolism of heme take place?

A

Spleen, then liver and finally intestines. may also occur in bone marrow

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15
Q

What creaks down heme during tissue damage?

A

macrophages

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16
Q

what is the first substance produced by heme catabolism?

A

biliverdin

17
Q

Biliverdin is converted into what molecule?

A

bilirubin

18
Q

Where is bilirubin conjugated?

A

liver

19
Q

How is bilirubin secreted?

A

in bile

20
Q

Bacteria in the gut convert some of the bilirubin into what substance?

A

Urobilinogen

21
Q

What is the fate of urobilinogen?

A

reabsorbed, transported to the kidneys and converted into urobilin and excreted

22
Q

What are the 2 excretory pathways for heme catabolism?

A

feces and urine

23
Q

What role does H+ binding to hemoglobin have?

A

induces hemoglobin to unload its bound oxygen