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Hematology > hemoglobin and myoglobin > Flashcards

hemoglobin and myoglobin Flashcards

1
Q

blood contains what percentages or RBC?

A

40%

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2
Q

blood contains what percentages or WBC?

A

1%

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3
Q

blood contains what percentages or plasma?

A

59%

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4
Q

Hb ____ o2 in the alveoli in the lungs and dilivers o2 to tissues throughout the body

A

binds

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5
Q

Hb ____ in maintaining acid-base balancing the body by binding some CO2 produced by metabolism and releasing CO2 when HB reaches the lungs

A

assists

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6
Q

both functions of hemoglobin are dependent on

A

partial pressure

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7
Q

myoglobin is synthesized inside

A

muscle cells

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8
Q

myoglobin stores oxygen in muscles cells for use at times of high/low metabolic demand

A

high

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9
Q

structure of myoglobin

A
  • single polypeptide chain - 80% alpha helical - closely-packed tertiary structure
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10
Q

structure of hemoglobin

A
  • four polypeptide chains 2 alpha and 2 bets - strong hydrophobic interactions between alpha 1 and beta 1 and alpha ii and beta ii
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11
Q

hemoglobin can bind ____ O2 molecules because it has ____ heme molecules

A

4; 4

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12
Q

heme molecules are ____ bonded to subunits of myoglobin and hemoglobin

A

covalently

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13
Q

myoglobin can bind ____ O2 molecules because it has ____ heme molecules

A

1; 1

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14
Q

hemoglobin subunits have strong/weak ___ interactions between heterodimers alpha 1beta 1 and alpha II and beta II

A
  • weaker polar interactions
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15
Q

HbA

A

alpha2 beta2; 97-98% of total Hb in adult

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16
Q

HbA2

A

alpha2 delta 2 1.5-3% of total Hb in adult

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17
Q

HbF

A

alpha 2 gamma 2; fetal; 1 month gestation until near brith

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18
Q

Hb epsilon

A

embryonic Hb 1 week post-conception until birth

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19
Q

alpha globin genes are found on ____ chromosome

A

16

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20
Q

beta globin genes are found on ____ chromosome

A

11

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21
Q

glycosylation of ____ is a marker for chronically elevated blood sugar

A

of alpha2beta2 (HbA)

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22
Q

organ progression of Hb generation

A

yolk sac liver spleen bone marrow

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23
Q
A
  1. alpha
  2. beta
  3. delta
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24
Q

deletion of the globin gene leads to

A

thalassemia

25
Q

thalassemia

A

imbalance in globin chain synthesis

26
Q

pyrrole rings

A

coordinate covalent bonds to Fe2+

27
Q

hydrophobic/hydrophilic chains from the pyrrole rings interact with the surrounding alpha beta globin chains to stabilize heme binding

A

hydrophobic

28
Q

heme belongs to the class of pigments known as

A

porphyrins

29
Q

myoglobin binding curve is sigmodial/hyperbolic indicating a single constant affinty for O2

A

hyperbolic

30
Q

hemoglobin binding curve is sigmodial/hyperbolic indicating a changing affinty for O2

A

sigmodial

31
Q

P50

A

the parital pressure where 50% of the oxygen binding sites are occupied

32
Q

hemoglobin exists in two conformational forms

A

T (taut) and R (relaxed)

33
Q

the T conformation favors the

A

deoxy form (O2 release)

34
Q

the R conformation favors the

A

oxy form (O2 binding)

35
Q

O2 is a ____ regulator of Hb O2 binding

A

positive allosteric

36
Q

2,3 di-phosphoglycerate (2,3 DPG) AND 1,3 BISPHOSPHOGLYCERATE stabilizes the T/R conformation

A

T deoxy conformatoin allowing realse of oxygen to the tissues

37
Q

levels of 2,3 DPG increase

A

chronic COPD, pregnancy, high altitude, chronic anemia, and pregnancy

38
Q

levels of 2,3 DPG INCREASE IN HYPOXIA BECAUSE

A

at lower partial pressure more oxygen will be realsed to tissues

39
Q

carbonic anhydrase

A

enzynme that catalyzes

CO2 + H2O –> carbonic acid H2CO3

40
Q

haldane effect

A

favors synthesis of CO2 and H2O

41
Q

bohr effect

A

favors O2 release, protons bind to the Hb and favor T conformation

42
Q

increas in pH favors O2

A

binding

43
Q

decrease in pH favors O2

A

release

44
Q

fetal hemoglobin has a different beta chain that has a higher/lower affinity for O2

A

higher

45
Q

HbF binds 2,3 DPG _____ becuase the cavity is not as positively charged

A

poorly

46
Q

Hb F has a higher/lower O2 binding affinity than Hb A in the mother

A

higher

47
Q

what has the highest affinity for oxygen

A

myoglobin

48
Q

over 1100 Hb variants known most are the result of ____ mutations

A

point that change a single amino acid

49
Q

the most common Hb variant associated with significant pathology in the US is

A

betaS variant

50
Q

beta S variant is caused by

A

mutation at position 6 of B globin gene which changes Glu6 to Val6

51
Q

beta S mutation can lead to

A

sickle cell anemia

52
Q

which forms more readily carboxyhemoglobin or oxyhemoglobin?

A

carboxyhemoglobin

53
Q

compounds that inhibit oxygen binding

A

cyanide (CN-)

carbon monoxide (CO)

nitrogen dioxide (NO2)

hydrogen sulfide (h2s)

54
Q

cyanide (CN-)

carbon monoxide (CO)

nitrogen dioxide (NO2)

hydrogen sulfide (h2s)

inhibit hemoglobin by

A

competitive inhibition

55
Q

mutations that change any of the 3 aa to make the binding less hydrophobic and more hydrophilic result in

A

hereditary methemoglobinemia

56
Q

hereditary methemoglobinemia

A

characterized by cyanosis (blueish color of the skin) and brown color to blood

57
Q

cytochrome b5 reductase

A

Fe3+ –> Fe2+

58
Q

causes of methemoglobinemia

A
  • mutations in ytochrome b5 reductase
  • mutations in pentose phosphate pathway
59
Q

_____ normally reduces reactive oxygen species thereby preventing formation of methemoglobin

A

glutathione

Hematology (23 decks)

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