Which cell type has a head, a midpiece, and a flagellum?

Which cell type has a head, a midpiece, and a flagellum?

• A. Erythrocyte
• B. Neuron
• C. Ovum
• D. Sperm

Answer: (D)

Having a head, a midpiece, and a flagellum is a design suited for a cell that must travel to and fertilize an egg. The head contains the genetic material (and, in many species, an acrosome with enzymes to help penetrate the egg’s outer layers). The midpiece is packed with mitochondria to supply the energy needed for movement. The flagellum, or tail, provides propulsive motion to swim toward the egg. Among the common cell types, this combination is unique to sperm, enabling both delivery of DNA and motility. Erythrocytes lack a nucleus and organelles for movement, neurons are built for signaling with a cell body, dendrites, and an axon, and ova are large, non-motile cells without a flagellum.

Having a head, a midpiece, and a flagellum is a design suited for a cell that must travel to and fertilize an egg. The head contains the genetic material (and, in many species, an acrosome with enzymes to help penetrate the egg’s outer layers). The midpiece is packed with mitochondria to supply the energy needed for movement. The flagellum, or tail, provides propulsive motion to swim toward the egg. Among the common cell types, this combination is unique to sperm, enabling both delivery of DNA and motility. Erythrocytes lack a nucleus and organelles for movement, neurons are built for signaling with a cell body, dendrites, and an axon, and ova are large, non-motile cells without a flagellum.