In phagocytosis, white blood cells (phagocytes) engulf bacteria primarily by means of which cellular structure/process?

• A. Active transport through porin channels in the phagocyte membrane
• B. Assembly of a contractile ring to perform binary fission around the bacterium
• C. Passive diffusion of bacteria directly through the plasma membrane
• D. Extension of pseudopodia followed by formation of a phagosome

Answer: (D)

Verified step by step guidance

1. Understand that phagocytosis is a process used by certain white blood cells (phagocytes) to engulf and internalize bacteria or other particles.
2. Recognize that phagocytosis involves the cell membrane actively changing shape to surround the target particle, which is done by extending parts of the membrane called pseudopodia.
3. Know that pseudopodia are temporary, arm-like projections of the cytoplasm and plasma membrane that reach out and encircle the bacterium.
4. Once the bacterium is fully surrounded by pseudopodia, the membrane closes around it, forming an internal vesicle called a phagosome.
5. The phagosome then moves inside the cell where it can fuse with lysosomes to digest the engulfed bacterium.