What are phagocytosis, endocytosis, and autophagy?

Phagocytosis is the process by which one cell engulfs another cell or large particle. For example, white blood cells present in the body engulf harmful microorganisms that enter the body through phagocytosis.

Endocytosis is the process involving the bulk transport of materials into the cell through membranes. It occurs by the infolding or extension of cell surface membrane to form a vesicle or vacuole. Endocytosis occurs by an infolding or extension of the cell surface membrane to form a vesicle. It is of two types, pinocytosis (cell drinking) and phagocytosis (cell eating). Endocytosis occurs through pseudopodia in amoeba.

Autophagy is a process by which unwanted structures within the cell are engulfed and digested within lysosomes. They are first enclosed by a single membrane, usually derived from smooth endoplasmic reticulum and this structure then fuses with a lysosome to form an 'autophagic vacuole', in which the unwanted material is digested.