Lysosomes are membrane-bound organelles found in nearly all animal cells that contain hydrolytic enzymes to break down biomolecules. They vary in size from 0.1 to 1.2 μm and have an acidic interior pH of 4.5 to 5.0. Lysosomes contain over 50 enzymes and mutations in these enzymes' genes cause lysosomal storage diseases. Lysosomes are involved in processes like secretion, plasma membrane repair, signaling, and metabolism beyond polymer degradation. They aid in phagocytosis and autophagy by fusing with phagosomes and autophagosomes respectively to digest engulfed contents.

1. Lysosomes

2.  A lysosome is a membrane-bound organelle found in nearly all animal
cells.
 Which contain hydrolytic enzymes that can break down many kinds of
biomolecules.
 Besides degradation of polymers, the lysosome is involved in various
cell processes, like secretion, plasma membrane repair, cell signaling,
and energy metabolism.

3.  The size of lysosomes varies from 0.1 μm to 1.2 μm.
 With a pH ranging from 4.5 to 5.0, the interior of the lysosomes
is acidic compared to the slightly basic cytosol (pH 7.2).

4.  Lysosome contains at least 50 different hydrolytic enzymes.
 Mutations in the genes that encode these enzymes are responsible
for more than 30 different human genetic diseases, which are called
lysosomal storage diseases.
 For example, Gaucher disease results from a mutation in the gene
that encodes a lysosomal enzyme required for the breakdown of
glycolipids.


5. Enzyme Substrate
Nucleases:
Acid ribonuclease RNA
Acid deoxyribonuclease DNA
Proteases:
Collagenase Collagen
Polysaccharidases and oligosaccharidases:
Glucosidase Glycogen
Fucosidase Fucosyl-oligosaccharides
Lipid hydrolyzing enzymes:
Acid lipase Triacylglycerols
Phospholipase Phospholipids

6. Formation of Lysosomes:
 Lysosomes tiny vesicles that separate, or "buded", from the ends
of the Golgi body (Trans Glogi).
 Vesicles formed in this way that contain enzymes such as
proteases, nucleases and lipases etc are called primary lysosomes.
 Secondary lysosomes are formed when primary lysosomes fusion
with other membrane-bound vesicles (eg. Phagosomes).

7. Phagocytosis :
 In phagocytosis, specialized cells, such as macrophages, take up and
degrade large particles, like bacteria, cell debris, and aged cells.
 Such large particles are taken up in phagosomes, which then fuse
with lysosomes and form phagolysosome, resulting in digestion of
their contents.

8. Autophagy:
 Lysosomes are also responsible for autophagy, the gradual
turnover of the cell's own components or organells.
 The first step of autophagy appears to be the enclosure of an
organelle (e.g., a mitochondrion) in membrane derived from the ER.
 The resulting vesicle called Autophagosome, it fuses with a
lysosome and form Autolysosome and digested the components or
organells.

9. How many lysosomes are present in a typical cell ?
 Many human cells contain hundreds of lysosomes while phagocytic
cells often contain thousands of lysosomes.
 Erythrocytes (red blood cells) do not contain any lysosomes.
 Lysosomes are particularly abundant in secretory cells e.g.
epithelial cells and in the kidneys..