LYSOSOMES (ENZYMES PACKETS)

Cell of Class 9

(a) Nature and occurrence

Discovered by Christian de Duve (1955) in rat liver cells.
Are tiny spherical sac-like structures surrounded by a single, thin bio-membrane which contain digestive enzymes (like hydrolases) for intracellular digestion and waste disposal.
Lysosomal enzymes are made by RER.
it is abundant in digestive glands.
The most important enzyme in lysosome is acid phosphates.
They are polymorphic in structure –
Primary Lysosome contains inactive enzyme.
Secondary Lysosome or Hetrosome isproduced by the fusion of primary lysosome with phagosome.
Residual lysosome has undigestable material left behind.
Autophagic Lysosome is produced when primary lysosome fuse with unwanted cell organelles.

They serve as intracellular digestive system, hence, called digestive bags.
They destroy and digest any foreign material like bacteria, food as well as old organelles in the cell. This is called heterophagy.
Remove the worn out and poorly working cell organelles by digesting them, removing cell debris and are hence known as demolition squad, scavengers, cellular housekeepers. Thus, lysosomes form a garbage disposal system of the cell.
During breakdown of cell structure, when the cell gets damaged, lysosomes may burst and eat up their own cells. Therefore, they are also called suicidal bags of cell.

Lysosome

Structure of Lysosome