MODULE 3

Question 1

is the most common complex organic molecule in vertebrates.

Answer 1

Hemoglobin (Hgb or Hb)

Question 2

It comprises approximately 95% of the cytoplasmic content of RBCs.

Answer 2

Hemoglobin (Hgb or Hb)

Question 3

provides protection from denaturation in the plasma and loss through the kidneys

Answer 3

hemoglobin in RBCs

Question 4

concentration of hemoglobin within RBCs

Answer 4

34 g/dL

Question 5

molecular weight of hemoglobin within RBCs

Answer 5

64,000 Daltons

Question 6

Hemoglobin’s main function is to transport oxygen from the (?) and transport carbon dioxide from the (?) for exhalation.

Answer 6

lungs to tissues
tissues to the lungs

Question 7

Hemoglobin also contributes to (?) by binding and releasing hydrogen ions and transports nitric oxide (NO)

Answer 7

acid-base balance

Question 8

a regulator of vascular tone

Answer 8

nitric oxide (NO),

Question 9

Components of Hemoglobin

Answer 9

1. Four heme molecules each composed of:
   a. The nitrogenous substance, protoporphyrin IX
   b. Iron atom in the ferrous (Fe2+) state.
2. The protein component known as globin made up of two sets or dimers of two different polypeptide chains.
3. The transient resident, 2,3-biphosphoglycerate (2,3-BPG) which regulates oxygen affinity to the hemoglobin molecule

Question 10

1. Four heme molecules each composed of:
   a. The nitrogenous substance, (?)
   b. Iron atom in the (?) state.

Answer 10

protoporphyrin IX
ferrous (Fe2+)

Question 11

2. The protein component known as (?) made up of two sets or dimers of two different polypeptide chains.

Answer 11

globin

Question 12

3. The transient resident, (?) which regulates oxygen affinity to the hemoglobin molecule

Answer 12

2,3-biphosphoglycerate (2,3-BPG)

Question 13

Structure of the Hemoglobin Components

Answer 13

1. Heme molecule
2. Globin molecule
3. The Complete Hemoglobin Molecule

Question 14

consists of a ring of carbon, hydrogen, and nitrogen atoms called protoporphyrin IX, with a central atom of divalent ferrous iron (Fe2+)

Answer 14

Heme

Question 15

Each of the (?) is positioned in a pocket of the polypeptide chain near the surface of the hemoglobin molecule.

Answer 15

four heme groups

Question 16

The (?) in each heme molecule reversibly combines with one oxygen molecule.

Answer 16

ferrous iron

Question 17

When the ferrous irons are oxidized to the ferric state (Fe3+) the hemoglobin will become (?), which cannot bind oxygen.

Answer 17

methemoglobin

Question 18

The (?) comprising each hemoglobin molecule consist of two identical pairs of unlike polypeptide chains, 141 to 146 amino acids each.

Answer 18

four globin chains

Question 19

Variations in amino acid sequences give rise to different types of

Answer 19

polypeptide chains.

Question 20

Each chain is designated by a

Answer 20

Greek letter

Question 21

The hemoglobin molecule can be described by its (?) structures.

Answer 21

primary, secondary, tertiary, and quaternary protein

Question 22

refers to the amino acid sequence of the polypeptide chains.

Answer 22

primary structure

Question 23

refers to chain arrangements in helices and non-helices

Answer 23

secondary structure

Question 24

refers to the arrangement of the helices into a pretzel-like configuration

Answer 24

tertiary structure

Question 25

loop to form a cleft pocket for heme

Answer 25

Globin chains

Question 26

Each globin chain contains a heme group that is suspended between the (?) of the polypeptide chain

Answer 26

E and F helices

Question 27

The (?) at the center of the protoporphyrin IX ring of heme is positioned between two histidine radicals.

Answer 27

iron atom

Question 28

Globin chain amino acids in the (?) are hydrophobic

Answer 28

cleft

Question 29

Globin chain amino acids on the (?) are hydrophilic, which renders the molecule water soluble.

Answer 29

outside

Question 30

This arrangement also helps iron remain in its (?) form regardless of whether it is oxygenated or deoxygenated

Answer 30

divalent ferrous

Question 31

(carrying an oxygen molecule)

Answer 31

oxygenated

Question 32

(not carrying an oxygen molecule).

Answer 32

deoxygenated

Question 33

also called a tetramer; describes the complete hemoglobin molecule.

Answer 33

quaternary structure

Question 34

The complete hemoglobin molecule is (?), has four heme groups attached to four polypeptide chains, and may carry up to four molecules of oxygen

Answer 34

spherical

Question 35

The predominant adult hemoglobin, (?) (also known as Hb A), is composed of two α-globin chains and two β-globin chains.

Answer 35

Hb A1

Question 36

hold the dimers in a stable form

Answer 36

Strong α1–β1 and α2–β2 bonds

Question 37

are important for the stability of the quaternary structure in the oxygenated and deoxygenated forms

Answer 37

α1–β2 and α2–β1 bonds

Answer 38

Alpha

Answer 39

Beta

Answer 40

Gamma A

Answer 41

Gamma G

Answer 42

Delta

Answer 43

Epsilon

Answer 44

Seta

Answer 45

Theta

Question 46

This is a substance produced in the anaerobic glycolytic (Embden-Meyerhof) pathway.

Answer 46

2,3-Biphosphoglycerate (2,3-BPG)

Question 47

This pathway generates energy for red blood cells.

Answer 47

Embden-Meyerhof

Question 48

is specifically produced in the by-pass pathway within the Embden Meyerhof pathway which is known as the Luebering-Rapoport Shunt.

Answer 48

2,3-BPG

Question 49

O2 affinity decreases

Answer 49

Hgb binds 2,3-BPG

Question 50

oxygen affinity increases

Answer 50

Hgb releases the 2,3-BPG

Question 51

This illustrates the reverse relationship between the amount of 2,3-BPG and the affinity of Hgb for O2.

Answer 51

Luebering-Rapoport Shunt

Question 52

How is Hemoglobin synthesized by the red blood cells?

Answer 52

A. Heme Biosynthesis
B. Globin Biosynthesis
C. Hemoglobin Assembly (Heme + Globin)
D. Development of Hemoglobin from fetal to adult life (Switching of globin chains)

Question 53

The biosynthesis of heme occurs mainly in the (?) of the bone marrow red cell precursors starting from the pronormoblast through the circulating reticulocytes.

Answer 53

mitochondria and the cytoplasm

Question 54

As the red cell further matures and lose their (?), they lose their ability to further synthesize hemoglobin.

Answer 54

ribosomes and mitochondria

Question 55

Heme biosynthesis begins in the mitochondria with the condensation of (?) catalyzed by aminolevulinate synthase to form (?)

Answer 55

glycine and succinyl coenzyme A (CoA)
aminolevulinic acid (ALA)

Question 56

In the cytoplasm, ALA undergoes several transformations from (?) to (?), which, catalyzed by (?), becomes (?).

Answer 56

porphobilinogen
coproporphyrinogen III
coproporphyrinogen oxidase
protoporphyrinogen IX

Question 57

In the mitochondria, (?) is converted to (?) by (?).

Answer 57

protoporphyrinogen IX
protoporphyrin IX
protoporphyrinogen oxidase

Question 58

(?) is added, catalyzed by (?) to form heme.

Answer 58

Ferrous (Fe2+) ion
ferrochelatase

Question 59

In the cytoplasm, heme assembles with an α chain and non-a chain, forming a dimer, and ultimately two dimers join to form the

Answer 59

hemoglobin tetramer

Question 60

(?), a plasma protein, carries iron in the ferric (Fe3+) form to developing erythroid cells.

Answer 60

Transferrin

Question 61

(?) binds to transferrin receptors on erythroid precursor cell membranes and the receptors and transferrin (with bound iron) are brought into the cell in an endosome.

Answer 61

Transferrin

Question 62

releases the iron from transferrin

Answer 62

Acidification of the endosome

Question 63

Iron is transported out of the endosome and into the mitochondria where it is reduced to the ferrous state, and is united with (?) to make heme.

Answer 63

protoporphyrin IX

Question 64

Heme leaves the mitochondria and is joined to the

Answer 64

globin chains in the cytoplasm

Question 65

code for six globin chains

Answer 65

Six structural genes

Question 66

are on the short arm of chromosome 16

Answer 66

α- and ζ-globin genes

Question 67

is on the short arm of chromosome 11

Answer 67

ε-, γ-, δ-, and β-globin gene cluster

Question 68

In the human genome, there is one copy of each globin gene per chromatid, for a total of (?), with the exception of a and g.

Answer 68

two genes per diploid cell

Question 69

There are two copies of the a- and γ-globin genes per chromatid, for a total of

Answer 69

four genes per diploid cell

Question 70

The production of globin chains takes place in (?) from the pronormoblast through the circulating polychromatic erythrocyte, but not in the mature erythrocyte.

Answer 70

erythroid precursors

Question 71

Transcription of the globin genes to messenger ribonucleic acid (mRNA) occurs in the

Answer 71

nucleus

Question 72

translation of mRNA to the globin polypeptide chain occurs on

Answer 72

ribosomes in the cytoplasm

Question 73

Although transcription of the a-globin genes produces more mRNA than the b-globin gene, there is less efficient translation of the

Answer 73

a-globin mRNA

Question 74

are produced in approximately equal amounts

Answer 74

a and b chains

Question 75

After translation is complete, the chains are released from the (?) in the cytoplasm.

Answer 75

ribosomes

Question 76

After their release from ribosomes, each globin chain binds to a heme molecule, then forms a

Answer 76

heterodimer

Question 77

have a charge difference that determines their affinity to bind to the α chains.

Answer 77

non-a chains

Question 78

has a positive charge and has the highest affinity for a β chain due to its negative charge

Answer 78

α chain

Question 79

has the next highest affinity, followed by the δ-globin chain

Answer 79

γ-globin chain

Question 80

Two heterodimers then combine to form a (?)

This completes the hemoglobin molecule.

Answer 80

tetramer

Question 81

Two a and two β chains form (?), the major hemoglobin present from 6 months of age through adulthood

Answer 81

Hb A

Question 82

contains two a and two δ chains

Answer 82

Hb A2

Question 83

Owing to a mutation in the promoter region of the δ-globin gene, production of the (?) is very low.

Answer 83

δ chain polypeptide

Question 84

comprises less than 3.5% of total hemoglobin in adults

Answer 84

Hb A2

Question 85

contains two a and two γ chains

Answer 85

Hb F

Question 86

In healthy adults, (?) comprises 1% to 2% of total hemoglobin, and it is present only in a small proportion of the RBCs (uneven distribution).

Answer 86

Hb F

Question 87

These RBCs with Hb F are called

Answer 87

F or A/F cells

Question 88

The various amino acids that comprise the globin chains affect the net charge of the

Answer 88

hemoglobin tetramer

Question 89

are used for fractionation, presumptive identification, and quantification of normal hemoglobin and hemoglobin variants

Answer 89

Electrophoresis and high-performance liquid chromatography (HPLC)

Question 90

(?) of globin gene DNA provides definitive identification of variant hemoglobin.

Answer 90

Molecular genetic testing

Question 91

Hemoglobin composition differs with

Answer 91

prenatal gestation time and postnatal age

Question 92

Hemoglobin changes reflect the sequential activation and inactivation (or switching) of the globin genes, progressing from the (?) on chromosome 16 and from the (?) on chromosome 11.

Answer 92

ζ- to the a-globin gene
ε- to the γ-, δ-, and β-globin genes

Question 93

normally appear only during the first 3 months of embryonic development.

Answer 93

ζ- and ε-globin chains

Question 94

These two chains, when paired with the a and γ chains, form the

Answer 94

embryonic hemoglobins

Question 95

During the second and third trimesters of fetal life and at birth, (?) is the predominant hemoglobin.

Answer 95

Hb F (a2γ2)

Question 96

By 6 months of age and through adulthood, (?) is the predominant hemoglobin, with small amounts of Hb A2 (a2δ2) and Hb F.

Answer 96

Hb A (a2β2)

Question 97

In utero, (?) predominates.

Answer 97

fetal hemoglobin

Question 98

When compared with adult hemoglobin, fetal hemoglobin has (?), a characteristic that allows sufficient oxygen transfer to the fetus in the absence of gas exchange with the external environment due to the relatively hypoxic environment in utero.

Answer 98

very high oxygen-binding capacity

Question 99

As a result, the hemoglobin level in a near-term fetus or term infant is relatively high and remains elevated up to around the (?) to compensate for the high oxygen affinity of hemoglobin.

Answer 99

8th to the 12th week post-partum

Question 100

reference intervals for hemoglobin concentration

Men:

Answer 100

Men: 14 to 18 g/dL (140 to 180 g/L)

Question 101

reference intervals for hemoglobin concentration

Women:

Answer 101

Women: 12 to 15 g/dL (120 to 150 g/L)

Question 102

reference intervals for hemoglobin concentration

Newborns:

Answer 102

Newborns: 16.5 to 21.5 g/dL (165 to 215 g/L)

Question 103

Reference intervals for infants and children vary according to

Answer 103

age group

Question 104

Individuals living at high altitudes have (?) as a compensatory mechanism to provide more oxygen to the tissues in the oxygen-thin air.

Answer 104

slightly higher levels of hemoglobin

Question 105

Hemoglobin variants are a part of the

Answer 105

normal embryonic and fetal development

Question 106

They may also be (?) of hemoglobin in a population, caused by variations in genetics.

Answer 106

pathologic mutant forms

Question 107

Some well-known hemoglobin variants, such as in sickle-cell anemia, are responsible for diseases and are considered (?).

Answer 107

hemoglobinopathies

Question 108

Other variants cause no detectable pathology, and are thus considered

Answer 108

non-pathological variants

Question 109

1. In the embryo (products of yolk sac erythroblasts)

Answer 109

• Gower 1 (ζ2ε2)
• Gower 2 (α2ε2)
• Hemoglobin Portland I (ζ2γ2)
• Hemoglobin Portland II (ζ2β2)

Question 110

2. In the fetus: (begins in early embryogenesis, peaks during third trimester and declines just before birth)

Answer 110

• Hemoglobin F (α2γ2).

Question 111

3. Right after birth up to before the first year of life:

Answer 111

• Hemoglobin F (α2γ2) at 60 – 90% of total Hb
• Hemoglobin A (adult hemoglobin) (α2β2) at 10 – 40% of total Hb.

Question 112

4. Two years through adulthood:

Answer 112

• Hemoglobin A (adult hemoglobin) (α2β2)
• Hemoglobin A2 (α2δ2)
• Hemoglobin F (fetal hemoglobin) (α2γ2)

Question 113

– 90% of total Hb

Answer 113

• Hemoglobin F (α2γ2) at 60

Question 114

– 40% of total Hb.

Answer 114

• Hemoglobin A (adult hemoglobin) (α2β2) at 10

Question 115

– The most common with a normal amount over 95%

Answer 115

• Hemoglobin A (adult hemoglobin) (α2β2)

Question 116

– δ chain synthesis begins late in the third trimester and, in adults, it has a normal range of 1.5–3.5%

Answer 116

• Hemoglobin A2 (α2δ2)

Question 117

– In adults Hemoglobin F is restricted to a limited population of red cells called F-cells (1 – 2%)

Answer 117

• Hemoglobin F (fetal hemoglobin) (α2γ2)

Question 118

B. Variant forms that may cause disease:

Answer 118

1. Hemoglobin D-Punjab (α2βD2)
2. Hemoglobin H (β4)
3. Hemoglobin Barts (γ4)
4. Hemoglobin S (α2βS2)
5. Hemoglobin C (α2βC2)
6. Hemoglobin E (α2βE2)
7. Hemoglobin AS
8. Hemoglobin SC

Question 119

A. Normal Hemoglobins

Question 120

is one of the sub-variants of Hemoglobin D, a variant of hemoglobin found in human blood

Answer 120

Hemoglobin D-Punjab (α2βD2)

Question 121

It is so named because of its higher prevalence in the Punjab region of India and Pakistan.

Answer 121

Hemoglobin D-Punjab (α2βD2)

Question 122

accounts for over 55% of the total hemoglobin variants there

Answer 122

Hemoglobin D-Punjab

Question 123

Hemoglobin D-Punjab was first discovered in the early 1950s in a mixed British and American family of Indian origin from the Los Angeles area; hence it is also sometimes called

Answer 123

“D Los Angeles”

Question 124

A variant form of hemoglobin, formed by a tetramer of β chains, which may be present in variants of α thalassemia.

Answer 124

Hemoglobin H (β4)

Question 125

Although each of the beta (β) globin chains is normal, the (?) does not function normally.

Answer 125

tetramer of 4 beta chains

Question 126

It has an increased affinity for oxygen, holding onto it instead of releasing it to the tissues and cells.

Answer 126

tetramer of 4 beta chains

Question 127

is also associated with significant breakdown of red blood cells (hemolysis) as it is unstable and tends to form solid structures within red blood cells

Answer 127

Hemoglobin H

Question 128

Serious medical problems are not common in people with (?), though they often have anemia.

Answer 128

hemoglobin H disease

Question 129

– A variant form of hemoglobin, formed by a tetramer of γ chains, which may be present in variants of α thalassemia.

Answer 129

Hemoglobin Barts (γ4)

Question 130

If a small amount of Hb Barts is detected, it usually disappears shortly after birth due to

Answer 130

dwindling gamma chain production

Question 131

These children have one or two alpha gene deletions and are silent carriers or have the alpha thalassemia trait.

Answer 131

Hemoglobin Barts (γ4)

Question 132

If a child has a large amount of Hb Barts, he or she usually has

Answer 132

hemoglobin H disease and a three-gene deletion

Question 133

have hydrops fetalis and usually do not survive without blood transfusions and bone marrow transplants

Answer 133

Fetuses with four-gene deletions

Question 134

– A variant form of hemoglobin found in people with sickle cell disease.

Answer 134

Hemoglobin S (α2βS2)

Question 135

There is a variation in the β-chain gene, causing a change in the properties of hemoglobin, which results in sickling of red blood cells.

Answer 135

Hemoglobin S (α2βS2)

Question 136

The gene defect is a single nucleotide mutation of the β-globin gene, which results in (?) being substituted by (?) at position 6 (E6V) substitution.

Answer 136

glutamic acid (E/Glu)
valine (V/Val)

Question 137

This is normally a benign mutation, causing no apparent effects on the secondary, tertiary, or quaternary structures of hemoglobin in conditions of normal oxygen concentration.

Answer 137

Hemoglobin S (α2βS2)

Question 138

However, under low oxygen concentration, (?) polymerizes and forms fibrous precipitates because the deoxy form of hemoglobin exposes a hydrophobic patch on the protein between the E and F helices.

Answer 138

HbS

Question 139

However, under low oxygen concentration, HbS polymerizes and forms fibrous precipitates because the deoxy form of hemoglobin exposes a hydrophobic patch on the protein between the E and F helices.

Question 140

– Another variant due to a variation in the β-chain gene

Answer 140

Hemoglobin C (α2βC2)

Question 141

Hb C or HbC is an abnormal hemoglobin in which substitution of a (?) residue with a (?) residue at the 6th position of the β-globin chain has occurred (E6K substitution).

Answer 141

glutamic acid
lysine

Question 142

This variant causes a mild chronic hemolytic anemia.

Answer 142

Hemoglobin C (α2βC2)

Question 143

E6V substitution

Answer 143

Hemoglobin S (α2βS2)

Question 144

E6K substitution

Answer 144

Hemoglobin C (α2βC2)

Question 145

E26K substitution

Answer 145

Hemoglobin E (α2βE2)

Question 146

– is an abnormal hemoglobin with a single point mutation in the β chain.

Answer 146

Hemoglobin E (α2βE2)

Question 147

At position 26 there is a change in the amino acid, from glutamic acid to lysine (E26K).

Answer 147

Hemoglobin E (α2βE2)

Question 148

is very common among people of Southeast Asian including Northeast Indian, East Asian descent

Answer 148

Hemoglobin E (α2βE2)

Question 149

This variant causes a mild chronic hemolytic anemia.

Answer 149

Hemoglobin E (α2βE2)

Question 150

– A heterozygous form causing sickle cell trait with one adult gene and one sickle cell disease gene.

Answer 150

Hemoglobin AS

Question 151

– A compound heterozygous form with one sickle gene and another encoding Hemoglobin C.

Answer 151

Hemoglobin SC

Question 152

These individuals have a mild hemolytic anemia and moderate enlargement of the spleen.

Answer 152

Hemoglobin SC

Question 153

Persons with Hb SC disease may develop the same (?) complications as seen in sickle cell anemia, but most cases are less severe.

Answer 153

vaso-occlusive (blood vessel-blocking)

Question 154

Patients with sickle cell trait (?) are protected from malaria.

Answer 154

(heterozygote for the sickle cell gene, Hb AS)

Question 155

• the process of measuring the concentration of hemoglobin in blood.

Answer 155

Hemoglobinometry

Question 156

• Determination of the concentration of hemoglobin in blood may be done using any of the following principles:

Answer 156

a. Methods based on the development of color when blood is mixed with a reagent.
b. A method based on specific gravity of the blood.
c. Measurement of oxygen combining capacity.
d. Indirect measurement using iron content.
e. By converting hemoglobin into one of several compounds and comparing the resulting compound with a known standard either visually or photoelectrically.
f. Electrical impedance or light absorption using automated hematology analyzers.

Question 157

Laboratory determination of hemoglobin concentration

Answer 157

1. Gravimetric Method (Specific gravity method or Copper Sulfate method)
2. Gasometric method (Oxygen capacity method)
3. Chemical method
4. Colorimetric method
5. Hemoglobin estimation using Automated Hematology Analyzers
6. Hemoglobin Electrophoresis

Question 158

– based on the estimation of specific gravity of blood, assuming that the patient has normal protein levels.

Answer 158

Gravimetric Method (Specific gravity method or Copper Sulfate method)

Question 159

Specific gravity of copper sulfate of 1.053 corresponds to an Hb level of

Answer 159

12.5 g/dL

Question 160

A drop of blood, allowed to fall into a copper sulfate solution of specific gravity 1.053, becomes encased in a +?), which prevents dispersion of fluid for 15 seconds

Answer 160

sac of copper proteinate

Question 161

a. If the drop of blood falls in a few seconds,

Answer 161

it has a greater specific gravity than the solution

Question 162

b. If the drop of blood rises in a few second,

Answer 162

it has a lower specific gravity than the solution

Question 163

c. If the drop of blood remains suspended for about 15 seconds and then falls,

Answer 163

more or less it has the same specific gravity as the solution

Question 164

This method is used by blood banks as a screening test for blood donors.

Answer 164

Gravimetric Method (Specific gravity method or Copper Sulfate method)

Question 165

In most cases, this method is capable of estimating Hb within ~0.5 g/dL, which is comparable to a coefficient of variation (CV) of 2%

Answer 165

Gravimetric Method (Specific gravity method or Copper Sulfate method)

Question 166

Based on the amount of oxygen in a given sample of blood, considering that hemoglobin will combine with and liberate a fixed quantity of oxygen.

Answer 166

Gasometric method (Oxygen capacity method)

Question 167

(?)

The blood is hemolyzed with (?) and the oxygen is collected and measured in a (?)

Answer 167

Gasometric method (Oxygen capacity method)

saponin
Van Slyke apparatus

Question 168

The oxygen combining capacity of blood is

Answer 168

1.34 ml O2 per gram of hemoglobin.

Question 169

The volume of oxygen is corrected for

Answer 169

temperature and pressure

Question 170

the hemoglobin concentration is determined with the use of the following formula:

Question 171

An indirect measure of hemoglobin based on the amount of iron for a given sample of blood.

Answer 171

Chemical method

Question 172

Based on the molecular structure, the iron content of hemoglobin is

Answer 172

0.347%

Question 173

Thus, 1 gram or 1000 mg of Hb contains (?) of iron.

Answer 173

3.47 mg

Question 174

The concentration of hemoglobin in blood is calculated by

Answer 174

dividing the iron content (mg/dl) by 3.47

Question 175

(?)

Iron is detached from the hemoglobin by treating the blood with (?) in the presence of (?).

Answer 175

Wong’s method

concentrated sulfuric acid
potassium persulfate

Question 176

(?)

The protein is precipitated with (?) and filtered out.

Answer 176

Wong’s method

tungstic acid

Question 177

The iron content of the filtrate is determined in a colorimeter and the Hb value is calculated with the following formula:

Question 178

The color of fresh blood is compared with a series of colored standards representing known quantities of hemoglobin.

Answer 178

Visual colorimetric method: Direct matching method

Question 179

• In this method drop of blood is placed on filter paper and the color is matched with standard (Fig. 3-5[A]).

Answer 179

▪ Tallquist method

Question 180

• In this method small glass chamber is filled with whole blood by capillary action. Then the glass chamber is illuminated by battery bulb. Color of the blood is matched with standard after seeing through eye piece.

Answer 180

▪ Dare’s method

Question 181

• In this method the color of diluted oxyhemoglobin is matched visually.

Answer 181

▪ Spencer’s method

Question 182

This method is less accurate than Sahli’s method. It is more difficult for the human eye to accurately grade and match small differences in red color than brown color of acid hematin.

Answer 182

▪ Spencer’s method

Question 183

• This technique of estimating hemoglobin is based on comparing the color of a drop of blood absorbed on a particular type of chromatography paper against a printed scale of color corresponding to different levels of hemoglobin ranging from 4 to 14 g/dl.

Answer 183

▪ WHO hemoglobin color scale method

Question 184

(?)

Blood is mixed with (?). This hemolyzes the red cells and converts the hemoglobin to a brownish yellow solution of acid hematin.

Answer 184

Acid hematin method

0.1 N HCl

Question 185

is then compared with a colored glass standard (Comparator Block)

Answer 185

acid hematin

Question 186

The procedures employed in the following are based on the principle of Acid Hematin method:

Answer 186

▪ Sahli – Hellige method
▪ Haiden – Hausser method
▪ Sahli – Adams method
▪ Osgood – Haskin method
▪ Haldane method
▪ Newcomer method

Question 187

▪ Sahli –

Answer 187

Hellige method
Adams method

Question 188

▪ Haiden –

Answer 188

Hausser method

Question 189

▪ Osgood –

Answer 189

Haskin method

Question 190

(?)

Blood is mixed with (?).

The solution is then boiled.

The hemoglobin is then converted to a blue–green solution of (?).

The color of the solution is then compared with a known standard or in a colorimeter

Answer 190

Alkali hematin method

0.1 N NaOH

alkaline hematin

Question 191

Alkali hematin method will not accurately measure the hemoglobin of an infant, because infant’s blood contains

Answer 191

alkali resistant fetal hemoglobin (HbF)

Question 192

The principle of Alkali – hematin method is used in the following:

Answer 192

▪ Standard method using Gibson and Harrison’s standard solution
▪ Clegg and King method

Question 193

Principle:

Blood is mixed with either 0.1% sodium carbonate or 0.007 N Ammonium hydroxide solution. This converts the Hb to oxyhemoglobin. The depth of the resulting color is then measured in a photometer with a green filter (540 nm) and 0.007 N ammonium hydroxide as a blank

Answer 193

Oxyhemoglobin method

Question 194

Principle:

Blood is diluted with Drabkin’s solution which contains ferricyanide and Cyanide. The potassium ferricyanide oxidizes hemoglobin to hemiglobin and potassium cyanide provides cyanide ions to form hemiglobincyanide, which has a broad absorption maximum at a wavelength of 540 nm. The absorbance of the solution is measured in a Photometer or spectrophotometer at 540 nm and compared with that of a standard HiCN solution.

Answer 194

Cyanmethemoglobin method (MHbCN method) or Hemiglobincyanide (HiCN) method

Question 195

The concentration of hemoglobin in MHbCN method is computed using the following formula:

Question 196

Hb determination is done by HiCN or the oxy-hemoglobin method. In the former, the blood specimen is diluted with a reagent containing ferricyanide and cyanide, which converts Hb to HiCN. The absorbance of the HiCN at 540 nm wavelength is then used for quantitation. In the latter, the blood specimen is diluted with an aqueous solution tetrasodium salt of ethylenediaminetetraacetic acid (EDTA) and mixed with air to convert Hb to oxyhemoglobin. The absorbance of oxyhemoglobin at 540 nm is then measured. A typical analyzer working on venous blood has a CV of ≤1.2% for Hb measurement.

Answer 196

Hemoglobin estimation using Automated Hematology Analyzers

Question 197

These analyzers have become increasingly sophisticated in the last few decades with the incorporation of noncyanide methods. Hb determination is done using sodium lauryl sulfate (SLS), a surfactant that dissolves lipoproteins of the cell membrane of the red blood cells to release Hb and converts it into SLS-Hb. Concentration of SLS-Hb is measured as light absorbance and is calculated by comparison with the absorbance of the diluent measured before the sample is added

Answer 197

Hemoglobin estimation using Automated Hematology Analyzers

Question 198

– Test for abnormal hemoglobins. This is generally considered the best method for separating and identifying hemoglobinopathies.

Answer 198

Hemoglobin Electrophoresis

Question 199

One protocol for hemoglobin electrophoresis involves the use of two systems:

Answer 199

Cellulose acetate and agarose medium
Citrate agar

Question 200

Initial electrophoresis is performed in alkaline buffers.

Answer 200

Cellulose acetate and agarose medium

Question 201

are the major support media used because they yield rapid separation of HbA, F, S and C and many other mutants with minimal preparation time.

Answer 201

Cellulose acetate and agarose medium

Question 202

because of the electrophoretic similarity of many structurally different hemoglobins, the evaluation must be supplemented by a procedure that measures some other property

Answer 202

Cellulose acetate and agarose medium

Question 203

A simple procedure which confirms the identification of both HbS and HbC, as well as HbA, HbF and many other mutants

Answer 203

Citrate agar electrophoresis

Question 204

This method is based on the complex interactions of the hemoglobin with the electrophoretic buffer (acid pH) and the agar support.

Answer 204

Citrate agar electrophoresis

Question 205

Because some hemoglobins have the same charge and, therefore, the same electrophoretic mobility patterns, hemoglobins that exhibit an (?) may be subjected to electrophoresis at an acid pH for definitive separation.

Answer 205

abnormal electrophoretic pattern at an alkaline pH

Question 206

In an acid pH some hemoglobins assume a negative charge and migrate toward the

Answer 206

anode

Question 207

while others are positively charged and migrate toward the

Answer 207

cathode (negative pole)

Question 208

Hb S migrates with Hb D and Hb G on (?) but separates from Hb D and Hb G on (?).

Answer 208

alkaline electrophoresis
acid electrophoresis

Question 209

Similarly, Hb C migrates with (?) on alkaline electrophoresis but separates on acid electrophoresis.

Answer 209

Hb E and Hb O

Question 210

The relative amount of hemoglobin is not proportional to the size of the band

Question 211

in sickle cell trait (Hb AS), the bands may appear equal, but the amount of HbA

Answer 211

exceeds that of HbS

Question 212

The main function of hemoglobin is to

Answer 212

transport oxygen.

Question 213

since oxygen is (?), it has to depend on hemoglobin found in red blood cells for its transport to the different organs and tissues of the human body

Answer 213

non-water soluble

Question 214

hemoglobin increases (?() in blood by about a hundredfold. this means that without hemoglobin, in order to provide sufficient oxygen to the tissues, blood would have to make a complete circuit through the body in less than a second, instead of the minute that it actually takes.

Answer 214

o2 solubility

Question 215

That would take a mighty powerful heart, which in normal circumstances cannot be maintained by the human heart leading to increased (?) that may result to heart failure.

Answer 215

cardiac output

Question 216

During oxygenation, each of the (?) in a hemoglobin molecule can reversibly bind one oxygen molecule.

Answer 216

four heme iron atoms

Question 217

Approximately (?) of oxygen is bound by each gram of hemoglobin.

Answer 217

1.34 mL

Question 218

Let’s follow the path of oxygen from the lungs to the peripheral tissues. Oxygen diffuses from the (?) of the lungs, little sacs at the end of the finely divided air passageways in the lung into the (?) of the bloodstream and then into the (?), where it binds to hemoglobin.

Answer 218

alveoli
capillaries
red blood cells

Question 219

The concentration of oxygen is relatively high in the alveoli, about (?) which means that Hb is virtually 100% saturated in the lungs and all four heme molecules have an O2 molecule bound to them.

Answer 219

100 mmHg

Question 220

The reference interval for arterial oxygen saturation is

Answer 220

96% to 100%

Question 221

The affinity of hemoglobin for oxygen relates to the (?)

Answer 221

partial pressure of oxygen (PO2)

Question 222

often defined in terms of the amount of oxygen needed to saturate 50% of hemoglobin, called the

Answer 222

P50 value

Question 223

The relationship is described by the (?), which plots the percent oxygen saturation of hemoglobin versus the PO2 (Figure 3-8).

Answer 223

oxygen dissociation curve of hemoglobin

Question 224

The curve is (?), which indicates low hemoglobin affinity for oxygen at low oxygen tension and high affinity for oxygen at high oxygen tension.

Answer 224

sigmoidal

Question 225

among hemoglobin subunits contributes to the shape of the curve.

Answer 225

Cooperation

Question 226

Hemoglobin that is completely (?) has little affinity for oxygen.

Answer 226

deoxygenated

Question 227

The secret to hemoglobin’s success as an oxygen delivery molecule is the fact that it has (?) that communicate to each other.

Answer 227

four subunits

Question 228

Evidence for this is provided by hemoglobin’s (?) in oxygen binding.

Answer 228

“cooperativity”

Question 229

In other words, the binding of one O2 molecule affects the binding of others, as we can see by the following:
• In order to achieve 25% saturation (an average of 1 O2 molecule per hemoglobin), the amount of O2 needs to be about (?).
• In order to achieve 50% saturation (an average of 2 O2 molecules per hemoglobin), the amount of O2 needs to be about (?).

Answer 229

18 mm Hg
27 mm Hg

Question 230

Therefore, it is easier to bind the than

Answer 230

second molecule of O2

Question 231

Nobel Prize winners for Chemistry for their studies of the structures of hemoglobin and myoglobin.

Answer 231

Max Perutz and John Kendrew

Question 232

Using (?), hemoglobin was found to have two different forms or shapes.

Answer 232

X-ray diffraction

Question 233

The (?) is dependent on the presence or absence of oxygen.

Answer 233

conformation or shape

Question 234

The experiments revealed that (?) has a relatively low attraction for oxygen, but when one molecule of oxygen binds to a heme group, the structure changes to the oxygenated form, which has a greater attraction for oxygen.

Therefore, the second molecule of O2 binds more easily, and the third, and fourth even more easily.

Answer 234

deoxyhemoglobin

Question 235

The oxygen affinity of (?) is many times greater than that of (?).

Answer 235

oxy-hemoglobin
deoxy-hemoglobin

Question 236

illustrates the relationship between oxygen saturation of hemoglobin and the partial pressure of oxygen.

Answer 236

oxygen dissociation curve

Question 237

In the Normal (N) hemoglobin-oxygen dissociation curve, P50 is the partial pressure of oxygen (O2) needed for

Answer 237

50% O2 saturation of hemoglobin

Question 238

In the Left-shifted (L) curve with reduced P50, it can be caused by decreases in (?) (e.g., multiple transfusion of stored blood), (?) (raised pH), (?) (PCO2), and/or (?).

Answer 238

2,3-bisphosphoglycerate
H+ ions
partial pressure of carbon dioxide
body temperature

Question 239

A left shifted curve is also seen with hemoglobin F and hemoglobin variants that have (?) and in alkalosis.

Answer 239

increased oxygen affinity

Question 240

In the (?) with increased P50 can be caused by elevations in 2,3-BPG (e.g., in response to hypoxic conditions such as in high altitudes), H+ ions (lowered pH), PCO2, and/or temperature.

Answer 240

Right-shifted (R) curve

Question 241

A right-shifted curve is also seen with (?) and in the presence of hemoglobin variants that have decreased oxygen affinity.

Answer 241

pulmonary insufficiency, congestive heart failure, sever anemia

Question 242

Factors that affect Hemoglobin affinity for Oxygen

Answer 242

1. Partial pressure of oxygen

Question 243

patient with arterial and venous PO2 levels in the reference intervals (80 to 100 mm Hg arterial and 30 to 50 mm Hg venous):

higher percent oxygen saturation
higher affinity for oxygen than a patient for whom the curve is normal

Answer 243

Shift to the left

Question 244

patient with arterial and venous PO2 levels in the reference intervals (80 to 100 mm Hg arterial and 30 to 50 mm Hg venous):

a lower oxygen affinity

Answer 244

shift to the right

Question 245

explains the lower affinity of hemoglobin for oxygen due to increases in the partial pressure of carbon dioxide (CO2) which eventually decreases the blood pH

Answer 245

Bohr effect

Question 246

Whenever the human body undergoes increased cellular respiration, such as in strenuous physical activities, there is also an increase in metabolic activity within the tissues involved resulting in the production of CO2 as a metabolic waste product.

Question 247

To transport CO2 through the venous blood, it diffuses into the red blood cells combining with water to form carbonic acid (H2CO3). This reaction is facilitated by the enzyme, carbonic anhydrase. The carbonic acid will then dissociate to release H+ and bicarbonate (HCO3-). The increase in H+ due to this reaction decreases the blood pH as explained by the Bohr effect.

Question 248

In addition to hydrogen ions and carbon dioxide, a key allosteric effector of hemoglobin is

Answer 248

2,3-Biphosphoglycerate (2,3-BPG)

Question 249

a small molecule made in red blood cells

Answer 249

2,3-Biphosphoglycerate

Question 250

affects oxygen-binding affinity by binding in a small central cavity of deoxygenated hemoglobin. This shifts the equilibrium towards deoxy-hemoglobin

Answer 250

2,3-BPG

Question 251

The presence of acids leads to:

Answer 251

• ↑ H+
• ↓ pH
• ↑ O2

Question 252

This promotes formation of the deoxy form of hemoglobin, shifting the oxygen dissociation curve to the right, promoting oxygen release to actively respiring tissues.

Answer 252

presence of acids

Question 253

At high altitude, when oxygen in the atmosphere is scarce because the air is “thinner,”:

Answer 253

• ↑ 2,3- BPG
• ↑ CO2
• ↓ O2

Question 254

(helping hemoglobin to release more of its bound oxygen = ↑ aerobic capacity)

Answer 254

• ↑ 2,3- BPG

Question 255

It takes about 24 hours forits levels to rise, and over longer periods of time, the levels continue to increase as part of the acclimation effect.

Answer 255

2,3-BPG

Question 256

2,3-BPG does not bind to fetal hemoglobin

Answer 256

• ↑ metabolic rates
• ↑ thermal energy
• ↑ average kinetic energy
• ↑ temperature
• ↓ affinity for oxygen

Question 256

Giving the developing fetus better access to oxygen from the mother’s bloodstream:

Answer 256

• ↑ 2,3- BPG

Question 256

This results in tighter binding of oxygen relative to maternal hemoglobin.

Answer 256

2,3-BPG does not bind to fetal hemoglobin

Question 257

.

Question 258

Hb decrease its affinity for oxygen to facilitate delivery to the tissues; shifts the oxygen dissociation curve to the right such as when tissues are actively engaged in physical activity, these tissues would require and eventually receive more O2.

Answer 258

• ↑ temperature

Question 258

Carbon dioxide

Answer 258

 ↑ cellular respiration
 ↑ metabolic activity
 ↑ CO2
 ↓ O2
 ↑ H+ ions
 ↑ 2,3-BPG

Question 258

In response to higher temperature, the Hb decrease its affinity for oxygen to facilitate delivery to the tissues. Thus, increased temperature in the blood shifts the oxygen dissociation curve to the right such as when tissues are actively engaged in physical activity, these tissues would require and eventually receive more O2.

Question 259

In response to higher temperature, the Hb decrease its affinity for oxygen to facilitate delivery to the tissues. Thus, increased temperature in the blood shifts the oxygen dissociation curve to the right such as when tissues are actively engaged in physical activity, these tissues would require and eventually receive more O2.