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Biochemistry I/II > Lectures 5 and 6 > Flashcards

Lectures 5 and 6 Flashcards

1
Q

What does elevated CR indicate?

A

Elevated CR = premature RBC loss (hemolytic anemia)

Normocytic and normochromic

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2
Q

What does a below average CR indicate?

A

Low CR = Not enough RBC’s being made

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3
Q

What does it mean if MCV is above normal?

A

Elevated MCV = Impaired DNA synthesis (Vit B12/Folate deficiency)

Macrocytic

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4
Q

What does it mean if MCV is below normal?

A

Low MCV = Impaired HGB synthesis (iron deficiency)

Microcytic and Hypochromic

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5
Q

What does it mean if MCV is normal?

A

Anemia is due to LOSS of HSC’s in bone marrow or loss of bone marrow stimulation (insufficient EPO made due to kidney dysfunction)

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6
Q

What is the cause of pernicious anemia?

A

Lack of intrinsic factor

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7
Q

Under what conditions is there decreased RBC Division?

A

Vit B12/folic acid deficiency

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8
Q

If one has Vit B12/Folic Acid deficiency, do the erythropoietic progenitors in the bone marrow have smaller or larger nuclei? Does HGB continue to be made?

A

larger; HGB continues to be made

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9
Q

In macrocytic anemia due to decreased RBC division, why are mature RBCs in blood larger (megaloblastic)?

A

Higher protein (HGB) content

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10
Q

How is MCV, HGB, and MCH affected in macrocytic anemia (vit deficiency?)

A

MCV = elevated
MCH (mean corpuscular hb) = elevated
total HGB = elevated
HGB = normal

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11
Q

How is MCHC affected in macrocytic anemia?

A

MCHC is normal

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12
Q

Adequate Iron is required in _____AND for ____synthesis and ___ production.

A

proerythroblasts ; ribosome ; HGB

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13
Q

Iron deficiency leads to production of ____ RBCs (low MCV) that contain less __

A

microcytic; HGB

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14
Q

True or False: Iron is required for the synthesis of hemoglobin and subsequent cell
division or erythroid precursors

A

True

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15
Q

Sources of iron?

A

1) Recycled from HGB from old or damaged RBCs
2) Diet

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16
Q

What type of anemia is associated with low MCV levels, iron deficiency, and impaired HGB synthesis?

A

Microcytic, hypochromic

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17
Q

What type of anemia is associated with elevated MCV and Vit B12/folate deficiency?

A

Macrocytic anemia

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18
Q

If MCV is within reference range, what type of anemia is the cause?

A

Loss of HSC’s in bone marrow or kidney disease
(normochromic and normocytic)

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19
Q

What can be determined by considering whether CR (correct reticulocyte count) is low or high?

A

Whether anemia is due to premature blood loss (eleavted) or impaired RBC production (low CR)

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20
Q

What can considering MCV help you to determine about one’s anemia?

A

Whether anemia is due to
1) nutritional deficiency/impaired DNA synthesis or
2) impaired HGB synthesis (iron deficiency)

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21
Q

____ is a genetic disorder affecting HGB production

A

Thalassemia

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22
Q

Chronic iron deficiency can lead to decreased production of ____ and ___ , less RBCs, and RBC’s that are microcytic and hypochromic

A

RBC and HGB

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23
Q

Three possible causes of Normocytic, normochromic anemia?

A

1) Acute blood loss
2) Pre-mature destruction of RBC
3) kidney or bone marrow damage

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24
Q

Microcytic, hypochromia is associated with what type of anemia?

A

Iron deficiency anemia

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25
Q

What type of anemia are Vit B12 and folate deficiencies are associated with?

A

Macrocytic, normochromic anemia

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26
Q

A normal response to RBC loss is release of ____ from the bone marrow stimulated by EPO (elevated CR)

A

reticulocytes

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27
Q

Premature RBC destruction/loss due to hemolysis or blood loss
results in _____ CR.

A

elevated

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28
Q

Deficient production of RBCs (i.e., insufficient bone marrow response to anemia) results in CR that is ______

A

within or below ref. range

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29
Q

Why might CR be within or below RR?

A
  • Decreased EPO production (kidney damage)
  • Decreased bone marrow mass
  • Decreased HGB synthesis
  • Decreased RBC precursor cell division
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30
Q

True or False: the reticulocytes:RBC ratio may be artificially low in
patients with anemia, CR considers the patient’s HCT compared
to normal HCT (~45%)

A

False - True or False: the reticulocytes:RBC ratio may be artificially high in
patients with anemia

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31
Q

True or False: Elevated CR > 0.5% - 2% represents increased reticulocyte production

A

True

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32
Q

Why are reticulocytes are larger than mature RBCs?

A

They contain ribosomes, mitochondria and RNA

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33
Q

In Vit B12/folate deficiency anemia, ___ is normal but ___ is elevated

A

MCHC (normochromic)
-because cell volume increases proportionately

MCH (increased Hb per cell)

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34
Q

Impaired DNA synthesis decreases ______

A

cell division

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35
Q

Routinely LOW MCHC is diagnostic for what type of anemia?

A

Iron deficiency anemia

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36
Q

MCH and MCHC generally parallel ____ values, because protein
content can impact cell size.

A

MCV

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37
Q

What value can help you determine is anemia is normochromatic or hypochromatic?

A

Mean Corpuscular Hb Concentration (MCHC)

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38
Q

What value can help you determine whether the anemia is micro or macrocytic?

A

Mean Corpuscular Volume (MCV)

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39
Q

True or False: The three types of anemia are:
-Fewer RBCs, normal size and HGB content
-Fewer RBCs, smaller with less HGB
-Fewer RBCs, larger with more HGB

A

True

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40
Q

What are the three measured CBC Indices?

A

1) [RBC] Red Blood Cell Concentration (Count)
2) [HGB] Hemoglobin Concentration
3) [HCT] Hematocrit

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41
Q

Three causes of anemia?

A

1) Premature RBC destruction (or blood loss)
2) Insufficient stimulation of erythropoiesis (kidney dysfunction)
3) Insufficient RBC production (Iron, folate and vitamin B12deficiencies)

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42
Q

Two substances that support adequate hemoglobin synthesis?

Substances that support adequate DNA synthesis and cell division of RBC precursors?

A

Iron and protein
Vit B12, folate, protein

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43
Q

What are the Corpuscular Indices?

A

-MCV
-MCH
-MCHC

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44
Q

True or False: Both hemoglobin and myoglobin are hemeproteins that contain heme as a prosthetic group

A

True

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45
Q

___: cofactor comprised of
iron (Fe2+) permanently associated with a
heterocyclic porphyrin ring

A

Heme

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46
Q

True or False: Heme is required for
the reversible binding of O2 by Hb and Mb

A

True

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47
Q

True or False: Hemoglobin undergoes irreversible cooperative binding of O2 via heme

A

False - hemoglobin undergoes reversible cooperative binding of O2 via heme

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48
Q

Hemoglobin carries O2 from the ___ to oxidatively active tissues to be released to fuel ___ of nutrients

A

lung; metabolism

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49
Q

True or False: Hemoglobin collects CO2 to be returned to the lungs, to be expelled

A

True

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50
Q

True or False: Myoglobin increases O2 availability to tissues by about 100-fold

A

False - Hemoglobin increases O2 availability to tissues by about 100-fold

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51
Q

Under what conditions does myoglobin store O2? release O2?

A

Stores O2: in resting muscle (due to high O2 binding affinity)

Releases O2: After muscle contraction (to replenish O2 supply)

52
Q

Myoglobin has a ___ structure while hemoglobin has a ___ structure

A

tertiary; quaternary

53
Q

Myoglobin contains a globin fold, which is comprised of 8 α-helical regions (80%) disrupted by a ___residue or by β-
____ and ___

A

proline; beta bends and loops

54
Q

True or False: Myoglobin is a monomer bound to Heme

A

True

55
Q

Myoglobin is stabilized by hydrophobic interactions between non-polar AA
in interior. Among these, are two basic ___ involved in binding heme

A

histidine

56
Q

In myoglobin, F8 binds ____ while E7 stabilizes ___ binding

A

heme Fe2+; O2

57
Q

Why is myoglobin water soluble?

A

Charged amino acids on surface form H2 bonds with each other and H2O

58
Q

Hemoglobin is a ___ comprised of 2 α-chains and 2 β-chains

A

tetramer

59
Q

Which has two identical α,β-dimers: Hemoglobin or Myoglobin?

A

Hemoglobin

60
Q

What is responsible for forming α,β-dimers in Hemoglobin?

A

Hydrophobic interactions in interior and exterior

61
Q

Which interactions maintain tetramer of Hb?

A

Weak ionic and hydrogen bonds

62
Q

Each globin subunit in Hb covalently binds ____ in heme, and each heme binds ___

A

Fe2+ iron; O2

63
Q

True or False: In Hb, no ionic and hydrogen bonds b/w alpha-beta dimers are broken in the oxygenated state

A

False

64
Q

Since there are low O2 levels in tissues, what state is Hb in while in tissues?

A

T state (deoxyhemoglobin)
- low O2 binding affinity

65
Q

There are __ O2 levels in tissues and __ O2 levels in the lungs

A

low; high

66
Q

What type of state is hemoglobin in while in the lungs?

A

R state (oxyhemoglobin)
- high O2 binding affinity

67
Q

True or False: In the lungs, globin subunits in tight conformation around heme iron does not allow O2-binding with high affinity

A

False - in low O2 levels in tissues, globin subunits in tight conformation around heme iron does not allow O2-binding with high affinity

68
Q

Where does O2 binding induces conformational change that relaxes globin binding to heme?

A

The lungs

69
Q

O2 binding to one Hb subunit alters its tertiary structure and increases the O2 binding affinity of other Hb subunits which alters the quaternary
structure of Hb – this “all or none” is also known as ____

A

cooperativity

70
Q

Balance shifts toward __ state in low O2
Balance shifts toward _ state in high O2.

A

T; R

71
Q

____: change in shape and/or activity of a protein induced by the binding of a
regulatory substance

A

Allosteric effects

72
Q

True or False: Hb is an allosteric protein

A

True

73
Q

____ is a positive homotropic effector

A

O2

74
Q

How many O2 molecules does hemoglobin bind? myoglobin?

A

Hemoglobin binds 4 O2 while myoglobin binds 1 O2

75
Q

Which has stronger O2 affinity — hemoglobin or myoglobin?

A

Myoglobin

76
Q

In the lungs….
___ is released from Hb
___ binds to Hb

A

CO2; O2

77
Q

In the tissues
____ binds to Hb
____ is released from Hb

A

CO2
O2

78
Q

T to R state transition occurs in the lungs or tissues?

A

Lungs

79
Q

Where is the high pO2? low pO2?

A

High pO2: lung alveoli
Low pO2: tissues

80
Q

Where is the O2 dissociation curve the steepest? How is this beneficial?

A

At the O2 concentration that occur in tissues
- Permits O2 delivery to respond to small changes in pO2

81
Q

When is Hb saturated with O2? When does OxyHb unloads O2 for oxidative metabolism?

A

lungs; in tissues

82
Q

Hemoglobin displays a ___ curve while myoglobin displays a ____curve

A

sigmoidal; hyperbolic (monomer)

83
Q

The higher the O2–binding affinity, the ___the P50

A

lower

84
Q

Where does Hb unloads O2 to Mb in?

A

In muscle

85
Q

Are CO2 (TCA cycle) and 2,3-BPG positive or negative allosteric effectors?

A

Negative allosteric effectors

86
Q

True or False: Combined effect of positive and negative allosteric effectors allows O2 availability to be fine-tuned in
tissues

A

True

87
Q

True or False: the T form of Hb is associated with low pH, high H binding, and high O2 release

A

True

88
Q

True or False: the R (oxyhemoglobin) form of Hb is associated with low pH, high H release, and high O2 binding

A

False - The R form of Hb is associated with HIGH pH, high H release, and high O2 binding

89
Q

Under what conditions do pCO2 and pH act as negative effectors, which DECREASE Hb affinity for O2?

A

High pCO2 and low pH

90
Q

Under what conditions is the T state stabilized and curve shifts to the right?

A

High pCO2 and low pH

91
Q

Does a decrease in pH result in a decreased or increased oxygen affinity of hemoglobin?

A

Decreased in pH causes decrease in O2 affinity of hemoglobin (right shift)

92
Q

True or False: At a lower pH, a greater pO2 is required to achieve any given O2 saturation

A

True

93
Q

____ explains how increased H+s and
pCO2 decrease O2 binding to Hb.

A

The Bohr effect

94
Q

Does DeoxyHb have a lower or higher affinity for H+ than oxyHb does?

A

higher

95
Q

True or False: There is a pH gradient between the lungs (higher pH) and tissues (lower pH) that permits RAPID loading or
unloading of O2 to tissues as required

A

True

96
Q

H+s bind to ionizable_____ side chains of Hb
and stabilize T state, which results in O2 release

A

histidine

97
Q

True or False: H+s that lower pH are also released when CO2 binds Hb

A

True

98
Q

CO2 is hydrated to ____ which binds to ____ amino groups of Hb subunits

A

carbamate ; N-terminal

99
Q

Where is this taking place?

A
100
Q

Is 2,3-BPG a positive or negative effector of Hb O2 affinity?

A

Negative effector

101
Q

2,3-BPG has a strongly negative charge
and allows strong ionic bonding to positively
charged amino acids located where?

A

Beta subunits of interior of deoxyHb

102
Q

True or False: When 2,3 BPG is present,
R state is stabilized and there is decreased O2-binding affinity

A

False - T state is stabilized and there is decrease O2 binding affinity

103
Q

2,3-BPG dissociates upon binding of ___ by Hb. The ____ charges in interior repel and the __ state is favored

A

O2; positive; R

104
Q

2,3-BPG shifts O2 dissociation curve to the ____

A

right

105
Q

What is a potential consequence of
giving a severely ill individual a
transfusion of stored blood having
decreased 2,3-BPG levels?

A

Inadequate O2 delivery due to favored
Hb R state.

106
Q

Carbon monoxide (CO) binds tightly (220X
greater than O2), but reversibly, to the Fe2+ ion in Hb to form _____

A

Carbon monoxyhemoglobin

107
Q

CO binding to 1 or more heme sites favors the __ form, and the O2 dissociation curve shifts to the ___. Why is this the case?

A

R; left

remaining globin subunits bind O2 with
increased affinity

108
Q

Is CO is a positive or negative allosteric effector of Hb?

A

Positive

109
Q

Under what conditions is there a transition from sigmoidal to hyperbolic curve?

A

CO exposure

110
Q

Hemoglobins are each comprised of two ___ subunits and two ___ or β-globin-like
subunits

A

α-globin; β-globin

111
Q

What is the major Hb in adults?

What Hb is found in fetus and newborn?

A

Hb A
Hb F

112
Q

Which has a higher affinity for O2: Hb F or Hb A? Why?

A

Hb F has higher affinity for O2 due to WEAK binding to 2,3 BPG (less positive larged AA in gamma-globin)

113
Q

____: family of genetic disorders caused by production of structurally abnormal Hb, synthesis of
insufficient quantities.

A

Hemoglobinopathies

114
Q

What are three diseases that can arise from
synthesis of abnormal globin subunits?

A

1) Sickle cell anemia (Hb S)
2) Hb C disease (Hb C)
3) Hb SC disease

115
Q

____ is characterized by insufficient synthesis of globin subunits

A

Thalassemias (α and β)

116
Q

____ is caused by a single base pair point
mutation (T to A) in the β-globin gene

A

Hb S

117
Q

In Hb S, a negatively charged ___ is substituted for a nonpolar, hydrophobic ___

A

glutamate, valine

118
Q

True or False: In Hb S, there is polymerization in the deoxygenated state

A

True

119
Q

_____ Hb S polymers form a network of fibers that stiffen and distort RBCs into the characteristic “sickle” cell shape

A

Deoxygenated

120
Q

True or False: The life span of an Hb S RBC is less than 20 days compared to 120 days for a normal RBC (premature destruction)

A

True

121
Q

True or False: variables that promote oxyHb can increase sickling!

A

False - variables that promote oxyHb can increase sickling!

122
Q

_____:Glutamate substitution with Lysine (Glu6Lys) to cause relatively mild,
chronic hemolytic anemia

A

Hb C disease (Hb C)

123
Q

____:Combination of βS and βC mutations in the same individual in the
“double heterozygous” state; less severe than Hb S with wide-ranging clinical variability

A

Hb SC disease (Hb SC)

124
Q

___: hereditary hemolytic diseases in which an imbalance occurs in the synthesis of globin
chains

A

Thalassemias

125
Q

β- (____) and α- (___) thalassemias

A

point mutations; deletions

126
Q

If one has thalassemias and
2 copies of β-globin gene, clinical onset is likely to occur several months after birth – with symptoms being: aggregation and
precipitation of excess α-subunits

A

True

127
Q

What happens to 2,3-BPG upon binding of O2 by Hb? positive charges in interior repel and the __state is favored

A

R state

Biochemistry I/II (23 decks)

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