Any factory needs a good maintenance crew to keep everything orderly, to get rid of the trash, and to dismantle and dispose of outmoded machinery. The maintenance crew also functions as a second line of defense. If someone gets past the security guard at the front door, it is usually the maintenance crew who catches the trespassers and chases them out. In a cell, the role of building maintenance crew is filled by the lysosomes. This is a very colorful description for some of the most unusual organelles in the cell.
Lysosomes are responsible for the breakdown and absorption of materials taken in by the cell.
During endocytosis, the cell membrane puckers up, forms a pouch around materials outside the cell, and pinches off to become a vesicle. If the contents need to be destroyed, lysosomes combine with the vesicle and release their enzymes. When a white blood cell engulfs a bacterium, it is the lysosomes that digest the bacteria. When a lysosome ruptures in a cell, it causes all of the cell's internal proteins to be digested. Autolysis allows an organism to eliminate worn-out cells.