Final answer:
Option (3), Hereditary spherocytosis is an inherited defect of the red blood cell's cytoskeleton, resulting in spherically shaped cells due to abnormalities in proteins like spectrin that are crucial for cell shape and flexibility.
Step-by-step explanation:
Hereditary spherocytosis is an inherited defect of the red blood cell (RBC) cytoskeleton. The cytoskeleton gives the cell its shape and mechanical properties, and in the case of hereditary spherocytosis, an abnormality in the RBC cytoskeleton leads to cells that are more spherical in shape and less flexible. This condition is due to defects in proteins such as spectrin, ankyrin, band 3, or protein 4.2, which are all parts of the cytoskeleton and critical for maintaining the cell's biconcave shape and structural integrity.
All cells, including RBCs, share a common structure with a plasma membrane, cytoplasm, DNA, and ribosomes. However, RBCs are unique as they lack a nucleus when mature, and instead rely heavily on their cytoskeleton and cell membrane for function. Hereditary spherocytosis is specifically related to an inherited defect in the cytoskeleton (Option 3), not the cytoplasm, nucleus, or cell membrane directly.