Lysosome
Lysosomes are membrane enclosed structures that can best be termed the garbage disposal units of the cell. They contain digestive enzymes that breakdown old organelles, food and foreign objects such as viruses and bacteria that may have been engulfed by the cell. The digestive enzymes require an acidic environment, of say around 4.5 pH, to work. By enclosing these enzymes in the membrane bound lysosome an acidic environment is created without damage to other organelles in the cell.

 

Lysosomes fuse with vesicles and dispense their enzymes digesting their contents of the vesicle.

Lysosomes are involved in autolysis and apoptosis( programmed cell death).

Autolysis is a process by which a cell self-destructs due to injury to the cell or dying tissue. It occurs when a lysosome allows the digestive enzymes out of its membranes.

Apoptosis is a form of programmed cell death rather than one that results from cell damage. This may occur at different times of development and include, cell breakdown during menstrual cycles and atrophy of certain hormone dependent tissues.