Sickle Cell Anemia - Term Paper Example

This pain can last from several hours to days. Chronic pain,lasting for weeks and months, is also possible. Recurring infections, gallstones, leg ulcers, multiple organ failure, spleen shrinkage and eye problems are due to the complications arising from sickle cell anemia (National Heart Lung and Blood Institute). Sickle cell anemia or sickle cell disease is due to a mutation, or a single nucleotide change in the gene or the DNA sequence that codes for hemoglobin. Hemoglobin is the major protein component of red blood cells and has the main function of transporting oxygen from the lungs to other organs in the body.

The single nucleotide change occurs at the codon GAG which codes for the amino acid glutamic acid. The adenine base or “A” is replaced with thymine, or “T”, resulting in GTG, which codes for amino acid valine (Berg, Tymoczko, & Stryer; US Department of Energy). Normal hemoglobin is HbA while sickle cell hemoglobin is designated as HbS (Figure 1). The change in the amino acid sequence of the hemoglobin gene results in significant changes in the structure of the hemoglobin protein, which ultimately lead to the shape alteration of red blood cells from concave discs to sickle shaped.

These alterations are due to the different properties of the two amino acids: valine is non-polar, while glutamic acid is electrically charged. At biological pH 7.4, glutamic acid has 2 negative charges. Mutant or sickle cell hemoglobin has less 2 negative charges compared to normal hemoglobin, therefore the interactions within the 4 chains of hemoglobin in red blood cells are affected, which changes the structure of the protein. A hydrophobic or “sticky” patch on the surface of the β chains of hemoglobin is produced.

When the hemoglobin molecules of the sickle cells is deoxygenated, they become insoluble and stick to each other, forming polymers or fibers, and the red blood cell