cell changes from a disc shapeto a sickled shape. In hemoglobin, there are four chains of amino acids. Two areknow as alpha chains, and two are called beta chains. In a normal hemoglobin,the amino acid in the sixth position on the beta chain is known as glutamic acid(refer to diagram 1.1 on page 6). During sickle cell anemia, the glutamic acidis pushed out of its place and replaced with another amino acid calledvialine(refer to diagram 1.2 on page 6). This simple substitution hasdevastating consequences. Hemoglobin molecules that contain the beta chain defect stick to oneanother instead of staying separate after releasing oxygen. This forms long,rigid rods inside the red blood cells. The rods cause the normally smooth anddisc shaped blood cells to take on a sickle shape. When this happens, the bloodcells lose essential ability to deform and squeeze through small blood vesselsand arteries. The sickle cells becomes stiff and sticky which clog vessels,depriving tissue from receiving a sufficient blood supply. This change makes thehemoglobin less soluble in water. When a person is deprived of oxygen, thehemoglobin molecules join together and form fibers. The fibers cause the bloodcells to change shape. Sickle hemoglobin and normal hemoglobin carry the same amount of oxygen butthere are two major differences between the two kinds of cells. The normalhemoglobin is found in only disc shaped red blood cells that are soft, whichpermits them to easily flow through small blood vessels. Diseased red bloodcells are sickle shaped and are very hard which tend to get stuck in small bloodvessels and stop the flow of blood. The other difference between the two cells is their longevity. Sickle cellsdo not live as long as normal cells. Normal healthy cells can survive for about120 days , while the more fragile sickle cells can survive for about 60 days oreven less. The body cannot make new red blood cells as fast as it loses sickledblood c...
