Sickle Cell Anemia Research Paper
SICKLE CELL ANAEMIA
Sickle cell anemia is an inherited condition. People with sickle cell anemia inherit two copies of the sickle cell gene, one from each parent. The sickle cell gene makes abnormal hemoglobin called Hemoglobin-S.
The sickle cell gene is a trait due to a change in ONE nucleotide in the DNA sequence that leads to a change in ONE amino acid that changes how the hemoglobin protein folds. This change in the structure of the hemoglobin protein leads to a change in the shape of the red blood cell to a sickle shape.
Sickle-cell anemia is caused by a point mutation in the B-globin chain of hemoglobin, replacing the amino acid glutamic acid with the less polar amino acid valine at the sixth position of the B chain. …show more content…
As seen above the single base change transforms an adenine base of an amino acid into a thymine base and this takes place in the 11th chromosome.
This changes the amino acid formed from glutamic acid to valine. Glutamic acid is hydrophilic while valine is hydrophobic causing the haemoglobin to collapse in on itself occasionally and this plays an important part in sickle cell anaemia.
Valine makes the haemoglobin less soluble under decreasing oxygen tensions.
Sickle cell hemoglobin exists as isolated units in the red blood cells when they have oxygen bound. However, when they release it in the peripheral tissues, due to valine, the molecules tend to stick together and form a polymer (long inflexible chain) which distorts the cell and causes it to bend out of shape. While most distorted cells are simply shaped irregularly, some of them have a crescent (or sickle)-like shape which gives it the disorder the name sickle cell anemia. When the red blood cells pick up oxygen again the chain breaks and the haemoglobin molecules are isolated
again.
The HbS polymerization prevents the use of oxygen by the hemoglobin. Oxygen molecules become a stable diradical and free electrons are incorporated by the oxygen molecules forming superoxide anions which attack the membrane and destroy fatty acids forming membrane lesions. The activated oxygen also oxidizes the HbS molecule turning it into meta HbS. The meta Hb S molecules join together forming Heinz bodies that precipitate towards the membrane and alters a protein and the arrangement of a molecule in the membrane.
The sickled red cells with membrane alterations impair the blood flow, causing vascular occlusion. Which causes tissue swelling and pain in the hands and feet.
The sickled red cells are then phagocytised by macrophages contributing to anaemia.
Normal red blood cells have a lifespan of around 120 days. When the haemoglobin molecule breaks down the iron joins the body’s iron pool and is recycled back into the new red blood cells. The other components of haem are broken down to bile pigments and excreted via the liver into the bile. In sickle cell anaemia, the red cells are destroyed early and increased amounts of the bile pigment bilirubin are produced, which can cause jaundice and build up of gallstones.
However, the advantage of having sickle cell anaemia is that you are protected from malaria because the parasite cannot feed so well inside sickle cells.
Sickle cell anemia is an inherited condition. People with sickle cell anemia inherit two copies of the sickle cell gene, one from each parent. The sickle cell gene makes abnormal hemoglobin called Hemoglobin-S.
The sickle cell gene is a trait due to a change in ONE nucleotide in the DNA sequence that leads to a change in ONE amino acid that changes how the hemoglobin protein folds. This change in the structure of the hemoglobin protein leads to a change in the shape of the red blood cell to a sickle shape.
Sickle-cell anemia is caused by a point mutation in the B-globin chain of hemoglobin, replacing the amino acid glutamic acid with the less polar amino acid valine at the sixth position of the B chain. …show more content…
As seen above the single base change transforms an adenine base of an amino acid into a thymine base and this takes place in the 11th chromosome.
This changes the amino acid formed from glutamic acid to valine. Glutamic acid is hydrophilic while valine is hydrophobic causing the haemoglobin to collapse in on itself occasionally and this plays an important part in sickle cell anaemia.
Valine makes the haemoglobin less soluble under decreasing oxygen tensions.
Sickle cell hemoglobin exists as isolated units in the red blood cells when they have oxygen bound. However, when they release it in the peripheral tissues, due to valine, the molecules tend to stick together and form a polymer (long inflexible chain) which distorts the cell and causes it to bend out of shape. While most distorted cells are simply shaped irregularly, some of them have a crescent (or sickle)-like shape which gives it the disorder the name sickle cell anemia. When the red blood cells pick up oxygen again the chain breaks and the haemoglobin molecules are isolated
again.
The HbS polymerization prevents the use of oxygen by the hemoglobin. Oxygen molecules become a stable diradical and free electrons are incorporated by the oxygen molecules forming superoxide anions which attack the membrane and destroy fatty acids forming membrane lesions. The activated oxygen also oxidizes the HbS molecule turning it into meta HbS. The meta Hb S molecules join together forming Heinz bodies that precipitate towards the membrane and alters a protein and the arrangement of a molecule in the membrane.
The sickled red cells with membrane alterations impair the blood flow, causing vascular occlusion. Which causes tissue swelling and pain in the hands and feet.
The sickled red cells are then phagocytised by macrophages contributing to anaemia.
Normal red blood cells have a lifespan of around 120 days. When the haemoglobin molecule breaks down the iron joins the body’s iron pool and is recycled back into the new red blood cells. The other components of haem are broken down to bile pigments and excreted via the liver into the bile. In sickle cell anaemia, the red cells are destroyed early and increased amounts of the bile pigment bilirubin are produced, which can cause jaundice and build up of gallstones.
However, the advantage of having sickle cell anaemia is that you are protected from malaria because the parasite cannot feed so well inside sickle cells.