Structure and Function of Hb Flashcards

1
Q

What shape does a hemoglobin molecule have

A

Tetrametric shape

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2
Q

What are the 4 types of hemoglobin

A

Adult Hb (HbA)

Fetal Hb (HbF)

HbA2

HbA1C

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3
Q

Which hemoglobin has 2 α and 2 β-chains

A

Adult Hb and HbA1C

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4
Q

Which hemoglobin has 2α and 2γ chains

A

Fetal Hb

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5
Q

Which hemoglobin has 2α and 2δ chains

A

Adult HbA2

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6
Q

What is another name for HbA1C

A

Glycated Hb

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7
Q

genes for beta chains are found on which chromosome

A

chromosome 11

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8
Q

genes for alpha chains are found on which chromosome

A

chromosome 16

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9
Q

which fetal site of globin synthesis is 12 weeks till birth

A

spleen

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10
Q

beta globins are missing from hemoglobin due to low transcription. which part of the gene is probably defected

A

locus control region

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11
Q

what type of porphyrin ring does Hb contain

A

protoporphyrin IX

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12
Q

Which form of iron contained in heme allows it to bind to oxygen

A

ferrous oxide (Fe2+)

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13
Q

A large amount of ferric oxide in Hb can indicate which pathological condition

A

Methemoglobinemia

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14
Q

What is the clinical presentation for a deficiency of NADH-metHb and what is the condition called

A

Cyanosis

Methemoglobinemia

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15
Q

drugs containing which suppose can lead to acquired methemoglobinemia

A

Nitrates

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16
Q

ferrous oxide is held in the center of the porphyrin rings of heme by which molecules

A

nirtogen

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17
Q

which globin chain has more alpha helical segments (alpha or beta)

18
Q

the proximal histidine around heme binds to _____ while the distal histidine stabilizes ____

19
Q

Which form of Hb is more abundant in the tissues? Why is this?

A

T-form because it has less affinity for O2 so O2 can be off loaded easier to tissues that need it

20
Q

Which form of Hb is more abundant in the lungs? Why is this?

A

R-form because it has a higher affinity for O2 and in the lungs the RBCs there need to hold on to the O2 they just received from the alveolar air

21
Q

myoglobin is mainly found in which tissues

A

Heart and skeletal muscles

22
Q

Pertaining to the structure of myoglobin why does it make sense that it’s dissociation curve is hyperbolic

A

it is monomeric, with only one heme group so it just accepts O2 until it;s saturated

23
Q

Pertaining to the structure of myoglobin why does it make sense that it’s dissociation curve is sigmoidal

A

it is tetrameric, so the one O2 binds which increases the affinity for more O2 so the slope of the curve increases as the consecutive sites get filled until they are all filled

24
Q

in which type of hemoglobin does the alpha globin chain have 8 alpha helical segments

25
Which four factors can influence loading and unloading of O2 in Hb
pH partial pressure CO2 partial pressure of O2 2,3-bisphosphoglycerate
26
a defect in the second half of glycolysis could potentially affect oxygen dissociation in Hb why?
in glycolysis, 1,3-bisphosphoglycerate is made which is used to make 2,3-bisphosphoglycerate which aids in oxygen dissociation
27
What factors affecting O2 dissociation would cause the a right shift in the O2 dissociation curve What does a right shift indicate
decreased CO2 high pH high 2,3-bisphosphoglycerate A right shift indicates more release of O2
28
What factors affecting O2 dissociation would cause the a left shift in the O2 dissociation curve What does a left shift indicate
increased CO2 low pH low 2,3-bisphosphoglycerate A left shift indicates less release of O2
29
A right shifted O2 dissociation curve more resembles which form of Hb Why is this?
T-form Because in the T-form, Hb has less affinity for O2 so there is more release of O2
30
A left shifted O2 dissociation curve more resembles which form of Hb Why is this?
R-form Because in the R-form, Hb has more affinity for O2 so there is less release of O2
31
Elevated 2,3-bisphosphoglycerate is seen in which conditions
Hypoxia (high altitude) and chronic anemia
32
Does 2,3-bisphosphoglycerate bind to alpha or beta chains
beta chain
33
Absence of what in HbF make them bind poorly to 2,3-bisphosphoglycerate
beta globin chain
34
Why does HbF need to have high affinity for O2
to trap maternal O2 for the fetus
35
What are the 4 main hemoglobinopathies
sickle cell anemia (HbS) hemoglobin C hemoglobin SC thalassemia
36
What is the defect in sickle cell anemia (HbS)
change of glutamic acid to valine in the 6th postion of the beta chain
37
What is the defect in HbC
change of glutamic acid to lysine in the 6th postion of the beta chain
38
Thalassemia is due to what
decreased Hb
39
Methylene blue can be used to treat a condition with a deficiency in which enzyme? What is the condition?
Deficiency in NADH-metHb reductase Methemoglobinemia
40
Carboxy hemoglobin causes Hb to be predominantly in which form? this leads to?
R-type Less O2 dissociation (hypoxia)