Question

Which statement explains how a DNA mutation causes sickle-cell anemia? (point)

Answer 1

Answer:

The DNA mutation causes a change in the amino acid sequence for hemoglobin, which causes a change in the shape of red blood cells.

Explanation:

Sickle cell anemia is one of a group of disorders known as sickle cell disease. Sickle cell anemia is an inherited red blood cell disorder in which there aren't enough healthy red blood cells to carry oxygen throughout your body.

Normally, the flexible, round red blood cells move easily through blood vessels. In sickle cell anemia, the red blood are shaped like sickles or crescent moons. These rigid, sticky cells can get stuck in small blood vessels, which can slow or block blood flow and oxygen to parts of the body.

Sickle cell anemia is caused by a mutation in the gene that tells your body to make the iron-rich compound that makes blood red and enables red blood cells to carry oxygen from your lungs throughout your body (hemoglobin). In sickle cell anemia, the abnormal hemoglobin causes red blood cells to become rigid, sticky and misshapen.

The sickle cell mutation reflects a single change in the amino acid building blocks of the oxygen-transport protein, hemoglobin. This protein, which is the component that gives red cells their color, has two subunits. The alpha subunit is normal in people with sickle cell disease. The beta subunit has the amino acid valine at position 6 instead of the glutamic acid that is normally present. The alteration is the basis of all the problems that occur in people with sickle cell disease.