Comparison Between Normal Red Blood Cells Characteristics And Sickle Cell – Article Example
Comparison between normal red blood cells characteristics and sickle cell Normal human red blood cells are biconcave disc shaped with a high capa for deformability (Diez-Silva et al. 382). Sickle cell red blood cells are present in individuals suffering from a type of structural hemoglobinopathy called sickle cell anemia. Normal adult red blood cells and sickle shaped red blood cells are different because of the dissimilar composition of the amino acid chain in their hemoglobin. Adult hemoglobin has two α globin chains and two β globin amino acid chains. It has been known for quite some years now that in sickle shaped red blood cells, glutamic acid of β globin polypeptide chain is replaced by valine (Diez-Silva et al. 382). Thus, polypeptide chains of hemoglobin are different in these two red blood cells phenotypes. Genetically, this replacement occurs as a result of missense single base mutation, wherein adenine is changed to thymine within the 6th codon. Negatively charged glutamic acid provides stability to the red blood cell structure and its loss leads to alteration in the electrophoretic mobility.
This altered phenotype of sickle cell is manifested in the deoxygenated state when the deoxygenated hemoglobin molecule undergoes conformational change into long polymers which distort the red blood cell into distinctive sickle shape, cause potassium leakage and increase the viscosity. Compared to normal adult red blood cells, sickle cells have reduced pliability and increased ‘stickiness’ so that they cannot traverse through small capillaries and adhere to the endothelium of small venules. Thus, sickle cells are more rigid and adherent as compared to normal red blood cells (Benz 669). Also, these cells are more prone to hemolysis in the spleen. After repeated cycles of shape change, these red blood cells become permanently sickled (Diez-Silva et al. 382).
Benz, Edward J. “Hemoglobinopathies.” Principles of Internal Medicine. Ed. Eugene Braunwald. New York: McGraw-Hill, 2003. 669. Print.
Diez-Silva, Monica et al. “Shape and Biomechanical Characteristics of Human Red Blood Cells in Health and Disease.” MRS Bull 35.5 (May 2010): 382–388. Web. 13 Nov. 2012