What does a red blood cell look like?

What does a red blood cell look like?

• A. Nucleated, round cell with a nucleus
• B. Biconcave disk shape, anucleate
• C. Rod-shaped with mitochondria
• D. Spherical with a central nucleus

Answer: (B)

Mature human red blood cells are specialized for carrying oxygen, so their appearance reflects that function. They have a biconcave disk shape, which dramatically increases surface area relative to volume and allows gas exchange to happen quickly. The concave design also makes them very flexible, so they can squeeze through tiny capillaries. In addition, they are anucleate, meaning they lack a nucleus, which frees up space to hold more hemoglobin—the protein that actually binds and transports oxygen. Because they don’t have a nucleus or mitochondria, they rely on glycolysis for energy. Descriptions involving a nucleated, round cell would describe immature RBCs or other leukocytes, not mature ones. A rod-shaped cell with mitochondria doesn’t match the RBC structure, since mature RBCs lack mitochondria. A spherical cell with a central nucleus is characteristic of many nucleated cells, not RBCs.

Mature human red blood cells are specialized for carrying oxygen, so their appearance reflects that function. They have a biconcave disk shape, which dramatically increases surface area relative to volume and allows gas exchange to happen quickly. The concave design also makes them very flexible, so they can squeeze through tiny capillaries. In addition, they are anucleate, meaning they lack a nucleus, which frees up space to hold more hemoglobin—the protein that actually binds and transports oxygen. Because they don’t have a nucleus or mitochondria, they rely on glycolysis for energy.

Descriptions involving a nucleated, round cell would describe immature RBCs or other leukocytes, not mature ones. A rod-shaped cell with mitochondria doesn’t match the RBC structure, since mature RBCs lack mitochondria. A spherical cell with a central nucleus is characteristic of many nucleated cells, not RBCs.