Human Sickle Cell Disease

Human Sickle Cell Disease - HbS molecules aggregate...

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Human Sickle Cell Disease (a.k.a. sickle cell anemia): Sickle cell disease is a human blood disorder that is caused by a single mutation in a gene that encodes one of the subunits of hemoglobin ( Hb) , namely β -globin. Hemoglobin is a tetrameric protein made up of two α -globin proteins, and two β - globin proteins; ααββ. Each of the 4 globin proteins embrace an iron-containing heme molecule (iron is what makes hemoglobin and Red Blood Cells red) whose function is to bind oxygen in the lungs and release it in all the tissues of the animal. The very simple change of the sixth amino acid in β - globin (glutamine is substituted with a valine) causes devastating consequences. It turns out that Hb containing β -globin subunits with the sickle mutation (known as HbS ) does not directly interfere with the ability of hemoglobin to store or release oxygen, but rather this amino acid change bestows a novel property on the hemoglobin molecule; in its deoxygenated state the
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Unformatted text preview: HbS molecules aggregate together to form polymeric fibers, and the presence of these fibers grossly distort the shape of Red Blood Cells (RBCs) . Instead of being shaped almost like a doughnut (without the actual hole) and having tremendous flexibility to squeeze through tiny capillaries within tissues, the aggregated HbS fibers cause the RBCs to become curved (like a sickle), rigid, prone to rupture and prone to clumping; rupture causes anemia and clumping clogs small blood vessels, leading to tissue damage. Sickle Cell Disease –An autosomalRecessive disorder of Hemoglobin A single mutation in the sixth amino acid of the β-globinchain (Glutamine -> Valine) causes Sickle Cell Disease•Red blood cells (RBCs) make up 40% of the blood volume•Hemoglobin makes up 70% of the proteins in RBCs Sickle RBCs Images removed due to copyright reasons. Images removed due to copyright...
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This note was uploaded on 11/05/2011 for the course BIOLOGY MCB2010 taught by Professor Jessicadigirolamo during the Fall '10 term at Broward College.

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