Question

What happens to the structure of hemoglobin in people with sickle cell disease when it is deoxygenated, and how can this influence the shape and integrity of an erythrocyte?

a) Hemoglobin becomes more flexible, promoting erythrocyte deformation.
b) Hemoglobin undergoes no structural changes during deoxygenation.
c) Hemoglobin forms long, rigid filaments, causing erythrocytes to assume a sickle shape.
d) Hemoglobin dissociates into individual subunits, leading to erythrocyte lysis.

Answer 1

In sickle cell disease, deoxygenated hemoglobin S forms rigid filaments, distorting erythrocytes into a sickle shape and causing various serious health complications.

Step-by-step explanation:

When hemoglobin in people with sickle cell disease is deoxygenated, it causes the hemoglobin to form long, rigid filaments. This structural change is due to the presence of abnormal hemoglobin, called hemoglobin S, which is the result of a single amino acid substitution in the protein. These long fibers cause the red blood cells to distort from their typical biconcave disc shape into a crescent or 'sickle' shape. The consequent rigidity and abnormal shape of the erythrocytes lead to a variety of complications, including the cells becoming lodged in narrow capillaries, obstructing blood flow and leading to serious health issues such as painful joints, delayed growth, and strokes. Hence, the correct answer is c) Hemoglobin forms long, rigid filaments, causing erythrocytes to assume a sickle shape.