Lysosomes are membrane-bound organelles containing enzymes to break down biological polymers, discovered by Christian de Duve. They have varied forms including primary, secondary, and tertiary lysosomes, each with distinct functions related to digestion and cell maintenance. Key roles include heterophagy, autolysis, and autophagy, essential for cellular processes in eukaryotic organisms.

1. PRESENTATION ON LYSOSOMES
Presented by : Bhanu Tiwari
B.Tech.Biotehnology
Dr.RPCAU Pusa

2. Exceptions
 Lysosomes is a membrane bound organelle that
contain an array of enzymes capable of breaking
down all types of biological polymers.
 Discovered by Christian De Duve in liver cells.
 Enzymes are acid hydrolytic in nature.
 pH of enzymes ranging from 4.5 to 5.0.
 Maintains pH differential by pumping protons(H+).
 Found in nearly all eukaryotes.
Absent in some fungi like yeast, neurospora.
Absent in some protists like Euglina.
Absent in meristemetic cells.
Also absent in mature mammalian RBC.
INTRODUCTION

3. Structure of lysosomes
Shape is generally spherical consist of only membrane and enzyme.
Size lies from 0.1 µm to 1.2 µm.
Lysosome number are more in the cells which are involved in
intracellular digestion like WBC, phagocytes, osteoclasts.
Lysosomes are polymorphic (multiple form )containg
different type of enzymes,divided into six categories.

4. ENZYMES SUBSTRATE
Proteoses Protein
Nucleases DNAase,RNAase
Glycosidases Glycosidic Bond
Esterases Ester Bond
Phosphatases Phosphate
Sulphatases Sulphate

5. Types/forms of lysosomes
 Primary lysosomes- primary lysosomes have inactive
Hydrolytic enzymes.
 Secondary lysosomes-lysosomes with active Hydrolytic
enzymes.
 Tertiary or residual lysosomes-poses and contain
undigested material.
 Autophagosomes or Autolysosomes-They help in digestion
of sparch of the cell. For eg. Mitochondria.they are also
called “suicidal bags”
 Primary,secondary and tertiary forms are collectively called
Heterophagosomes.

6. Functions of lysosomes
 Heterophagy - Digestion of
external
food/pathogens/molecules.
 Autolysis - Break down of
lysosomes itself by which entire
cell is digested or destroy.
 Destroy carcinogens
 Autophagy - Digestion of internal
material like Cell
organelles,molecules.
 In metamorphosis
Autophagy of mitochondria

7. Heterophagy

8. References
 Cell and Molecular Biology: Concept and Experiment, G.Karp
 Darnell, J.E.; Lodish, H.F.; Baltimore, D. Molecular Cell Biology, 2nd ed., Chapter 26.
New York:
 Alberts molecular biology.