Cell walls are only found in plant cells and are used primarily to create structure, but cell membranes are found in all cells.The bulk of the membrane is composed of a double layer of lipids called the lipid bilayer. Inside the bilayer there is a layer of cholesterol to keep the membrane fluid.
sickle cell anemia is caused by a mutation in the hemoglobin beta (or HBB) gene and it leads to a single change in amino acid sequence. this gene is located on chromosome 19
