Lysosome structure and function

lysosome- cell organelle forms of the lysosome, the function of lysosomes, Autophagy and Heterophagy mechanism

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 C hristian D e D uve 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 , ne u rospora. 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 - D igestion of external food/pathogens/molecules. Autolysis - Break down of lysosomes itself by which entire cell is digested or destroy. Destroy carcinogens Autophagy - D igestion of internal material like Cell organelle s, 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.