Identify The Two Unknown Hemoglobin Types Biology Essay


Normally, hemoglobin molecules are constituted of two pairs of globin chains, The heme group is situated in the center of the globin chain. The HbF is the main oxygen transport protein in the fetal life and the first few months of life. The HbF contain two alpha chains and two gamma chains (alpha 2 gamma 2). During the growth of the baby, the hemoglobin F is progressively replaced by the hemoglobin A which is the most common type of hemoglobin found in a normal adult.

The HbA contains two alpha chains and two beta chains (alpha 2 beta 2). Hemoglobin A2 is a normal type of hemoglobin found in small quantity in a normal adult. It consists of two alpha and two beta chains as described in the table, hemoglobin A2 may progress in some case in beta thalassemia. 

Hemoglobin C is one of hemoglobin variants caused as a result of genetic biparental inheritance in hemoglobin C. Hemoglobin C is consist of 2 normal alpha chains and 2 variant beta chains in which glutamic acid is substituted for lysine at position 6 of the globin chain . The unbalanced hemoglobin triggers the formation of crystals in red blood cells. These crystals in the RBC lead to a considerable decrease deformability in red blood cell and an increase in the thickness of the blood.

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Hemoglobin S is also another type of hemoglobinopathy that is caused by mutation in the hemoglobin beta gene. The mutation arises as the production of hemoglobin S which is the abnormal form of beta- globin.

This variant arises as a result of a change in amino acid in the beta-globin particularly glutamic acid is substituted by the amino acid Valine at the position 6 of the beta globin chain causing the abnormal Hemoglobin S subunits. Most of the hemoglobin variant or hemoglobinopathies are caused by a single mutation in the genetic code due to a substitution of amino acid. But some of them are caused as a result of two amino acid substitutions and some others originate from the mutation that deletes a stop codon in an amino acid yielding an unusually long and erratic molecule of hemoglobin.

Some hemoglobin variants are not pathogenic. A carrier of one these hemoglobin variant may not develop any diseases. Clinically and hematologically, few hemoglobin variants such as HbS has significant impact on the body. Hemoglobin S and hemoglobin C are the most common types of abnormal hemoglobins that may be found by an electrophoresis test. Homozygous progenitor (HbSS) received two identical copies of the HbS mutation from their parents and have the most serious disease phenotype. Heterozygous carriers (HbAS) in the other hand develop a usually non- malignant condition without clinical complications known as sickle cell trait. Even though Sickle Cell anemia is caused as a result of single mutation, the disorders present considerable heterogeneity due to genetic and environmental influences. The table below shows the genotypes and phenotypes related to the Hemoglobin variant mutation

Conditions names

Hemoglobin variants


Beta genotype

Sickle cell disease (HbSS)

HbS, HbF, HbA and HbA2



Sickle cell trait


HbA2 and




Sickle cell disease


HbA, HbA2 and

Rest HbS



Sickle cell disease (HbSC)

HbS, HbC and

Minimal HbA2



SCD (βS/+-thalassemia)


HbA and





Fig 1: image taken from the the cellulose acetate paper pH 8.4

Negative end (cathode)

From left to right:HbA,HbA,HbS HbF, HbF.

positive end (anode)


This unclear photograph was taken after the electrophoresis technique was performed on the cellulose acetate paper. The sample was stained with the Ponceau S stain. Below is a representative image of the same picture to enable the identification of bands

Fig 4: hand drawn diagram represents the cellulose acetate paper pH 8.4



Unknown 2

Unknown 1


Position to which hemoblogins have migrated: anode(+)

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Position to which hemoblogins have migrated: catode (-)


From left to right Hb A, Hb A, Hb S; by looking at the direction and distance of these and 2 unknowns hemoglobin we could determine that they are normal hemoglobin (HbA2) could be as they travel toward the negative end where the majority of normal hemoglobin migrated and both travel at the same distance approximately next to the known hemoglobin A2 loaded in the lane 2.

Fig 4: Migration distance (millimeter)

Anode (+)

Cathode (-)


8 mm

7 mm

3 mm

5 mm

5 mm

Fig 4: migration predicted of fetal haemoglobin (HbF) and haemoglobin C

Position to which hemoblogins have migrated: catode (-)

Normal haemoglobin


Partener samples

Position to which hemoblogins have migrated: catode (-)

(trait) Hemoglobin variant


The position of HbC and HbF on the cellulose acetate membrane was Based on the characteristic feature of the known hemoglobin given and the migration direction observed in figure the previous


Electrophoresis is an effective analytical tool used in genetic to separate charged molecules according to their size and charge. It uses cellulose acetate strip into a tray containing the TEB buffer at pH values of 8.9 In an electric field, the complexes or charged molecules  will migrate to either positive or negative electrode. Shorter molecules tend to move faster and their migration distance is considerable than longer molecule

The Hbs loaded in the third line of cellulose acetate migrated towards the positively charged anode suggest that the hemoglobin S is therefore a negatively charged molecule( anions) however the samples loaded in the first, second, and the two unknowns loaded in the fourth and fifth lanes, are positively charged molecule (cation) because they all migrated towards the negatively charged side ( cathode)

The components in the HbA

To determine the hemoglobin types, the technique uses an electrical current to separate normal and the aberrant types of hemoglobin (hemoglobin variant) in the blood as some types of human hemoglobin vary to some extent in the amino acid structure of their subunits.

To probably estimate the migration direction of fetal hemoglobin, If run on the electrophoresis gel, the HbF will probably migrate in the direction where hemoglobin A migrated which is the negative or cathode end. This could be justified as HbF, being a normal form of hemoglobin found in unborn and young babies, and progressively is replaced by the hemoglobin A which is the most common type of hemoglobin found in a normal adult; it is obvious that their migration in electrical field will probably go in the same direction.

The hemoglobin C on the other hand will probably migrate in the positive charge side (anode,+) where the HbS, a severe mutated form of hemoglobin migrated. This also could be justified as HbC is a heterozygous hemoglobin variant, their migration in fact will travel in the same direction where any affected hemoglobin migrated.

Sickle cell anemia results from a single base-pair mutation in the gene of the beta chain of Hb A , it is one of the most common and severe hemoglobinopathy affecting the function of erythrocyte and many organs in the body.

Hemoglobin in fact, is a tetramer consisting of 2 dimmers that bind to oxygen. It consist of 4 polypeptide subunit 2 alpha and 2 beta each beta globin chain consists of 146 amino acid.In the case of Sicke Cell Anemia, an adenine to the nitrogenous base thymine exchange in the sixth position of the codon replaces glutamic acid with Valine in the resulting β-globin chain.

As a result, mutated hemoglobin S binds oxygen less efficiently than normal hemoglobin. Glutamic acid is a hydrophilic molecule, it interacts favorably with water, valin in the other hand, is a hydrophobic, this produce a sticky spot on the surface of the beta subunits allowing the beta subunit of different hemoglobin to adhere to each other by polymerizing and form an elongated rode like fibre.

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The soluble fiber will lead to a sickle shape cellular. As the Red Blood Cells sicked, become fragile and form an insoluble gel, resulting in red blood cell decrease deformability, cell membrane damage, ruptured releasing enzymes called arginase into blood stream as a result nitric oxide which keep blood platelet cells from sticking together and relaxes smooth muscle (endothelial cells) of the vascular wall to improve blood flow cannot be produced therefore , haemolysis will reduce red blood cell number and lead to anemia.

Sickle cells then cling to the wall of blood vessels and blocked or impaired the blood flow as a result, oxygen levels will be impaired resulting in ischemia (insufficient supply of blood to organs ); less energy will be produced causing fatigue, lactic acid irritation and severe pain, additionally deprivation of oxygen may lead to avascular necrosis.

The obstruction in the joints, chest and abdomen cause severe discomfort   also called crisis.

The function of the spleen is to clear defective red blood cells, as the blood vessels of the spleen are narrowed, sickle cell can easily be trapped in the tiny vessel of spleen and cause hypoxia condition which is a lack or impair oxygen supply; as a result, blood cells are accumulated within the spleen and cause it to enlarge and infarct a result of loss of blood supply, scarred or leading to internal bleeding which could be fatal.

Splenic dysfunction is followed by atrophy of the spleen. As the spleen undergoes multiple episodes of tissue death, it eventually atrophies, or shrinks. In some cases, the spleen will disappear, this condition increase the change of contracting infectious disease. Furthermore, as blood cells are trapped within the spleen a substantial drop in the volume of RBC may occur, causing hypovolemic shock, in which insufficient amounts of blood are pumped throughout the body.

Repeated episodes of reduced blood flow will impair oxygen transport around the body therefore can result to organ damage such as liver damage. Reduced blood flow to the brain can cause the condition of hypoxia as the intracranial arteries is affected causing dizziness and fatigue and could lead to strokes and cerebral infarction, when the eyes are deprived of oxygen, blindness can develop. Sickle cell has a lifespan of 10-20 days. As the sicked cell shape cannot keep up the demand to replace dying red blood cells, the resulting deficit causes the symptoms of anaemia: fatigue, pale skin, and shortness of breath, acute chest syndrome also is caused by sickling in pulmonary arteries and fat embolization.As the damaged RBC cannot carry enough oxygen in the heart, it promote negative impact on blood flow which contributes to the vascular occlusion process, as blood flow is directly proportional to the blood pressure, and inversely proportional to the blood viscosity; increase activity of the heart and the amount of blood pumped on the chambers will cause high blood pressure

In the population level, sickle cell has been According to the National Institutes of Health ( ) the most common inherited blood disease affecting about 250 million people worldwide

Certain populations are at greater risk for developing different symptoms than others. Gene mutations in sickle cell possibly result from spontaneous in different geographic regions as implied researchers in restriction endonuclease analysis.