Lysosomes

1. Lysosomes are small vesicles which are bounded by a single membrane & contain hydrolytic enzymes in the form of minute crystalline or semi crystalline granules of 5-8 nm.
2. It is also known as Atom of the cell, Disposal unit, Suicidal bag, Lytic bags, Scavanger of the cell.
3. Lysosome were first observed by Novikoff.
4. Discovered by De Duve (1955) in liver cells and called it "Pericanalicular dense bodies"
5. Novikoff called it Lysosome and he also gave the term GERL = GB + ER + Lysosome. Relation between golgi body, endoplasmic reticulum and lysosomes is known as GERL system.
6. P. Matile (1964) discovered them in Neurospora. Lysosomes abundantly found in fungi.
7. Pit and Galpin (1973) confirmed their presence in higher plant cells (Potato stem).
8. With the exception of mammalian RBC they were reported from all animal cells.
9. In majority of plant cells large central vacuole functions as Lysosome. So in higher plants lysosomes are less frequent.
10. Periplasmic space - Space between cell wall and cell membrane in bacteria plays similar role.
11. Lysosomes are spherical bag like structures (0.1-0.8 m) covered by single unit membrane. They are larger in phagocytes (0.8 to 2 m).
12. Lysosomes are polymorphic cell organelles.