What cellular process involves the engulfing of large particles?

Phagocytosis is the cellular process through which cells engulf large particles, such as pathogens or cellular debris. This process is crucial for the immune system, allowing immune cells like macrophages and neutrophils to eliminate harmful entities from the body. During phagocytosis, the cell membrane extends around the particle, ultimately enclosing it in a vesicle known as a phagosome. This vesicle then typically fuses with lysosomes, where the engulfed material is degraded by enzymes.

In contrast, pinocytosis refers to the process of drinking small vesicles of extracellular fluid and solutes, which does not involve large particle engulfment. Exocytosis is the mechanism by which cells expel materials by vesicles fusing with the plasma membrane, thus releasing their contents outside the cell. Diffusion is a passive transport process that allows substances to move across cell membranes along a concentration gradient and does not involve the engulfing of particles at all.

Therefore, the process that specifically involves the engulfing of large particles is indeed phagocytosis.