Endoplasmic reticulum

ENDOPLASMIC RETICULUM (SMOOTH AND ROUGH).

1. ENDOPLASMIC RETICULUM BY- SHEETAL BISHT

2. CONTENTS INTRODUCTION TYPES OF ENDOPLASMIC RETICULUM STRUCTURE FUNCTION

3. INTRODUCTION HISTORY : First observed by light microscope and it was called ergastoplasm. Discovered by porter. It’s found in all Eukaryotic cell except Erythrocytes (RBC) of mammals. In prokaryotic cells it is absent. In muscle cells it is known as sarcoplasmic reticulum. Found undifferentiated and small in eggs and embryonic cell.

4. TYPES OF ENDOPLASMIC RETICULUM 1. Agranular / Smooth Endoplasmic Reticulum (SER) :- In these SER ribosomes are absent on the surface. It forms Lipid. These are spheroidal 50 – 500 nm in size. These are more abundant in glycogen storing liver cells, intestinal cells, adipose cell, leucocytes and retinal cells.

5. 2. Granular Reticulum / Rough Endoplasmic Reticulum (RER) :- Ribosomes are attached by riboprotein to RER. It’s found mostly that secrets material continuously. Protein synthesis occurs in presence of Ribosome. RER is the ergastoplasm or basophilic bodies or Nissel bodies. This is involved in metabolism and transport of protein.

6. STRUCTURE It’s double membranous organ. Endomembranes have 2 faces. Cytoplasmic or Protoplasmic Face – Ribosome present. Luminal Face. Following types of structure are found in it- 1. Cisternae : It’s elongated, flattened, and unbranched. These are about 40-50 µ thick.

7. 2. Tubules : Elongated, smooth walled/branched. Diameter – about 50-190 µ. Found in non-secretory cells like – muscle cells, develop in spermatid of guinea pig. 3. Vesicles : They are rounded, spherical. It’s found in which cells they are busy in protein synthesis and in liver and pancreatic cells. It forms organelles like spheriosome, peroxysome.

8. FUNCTION Cell Skeleton Formation. Rough ER form protein. Smooth ER form Lipid and Steroid. Segregation of protein.

9. Formation of Plasmodesmeta. Detoxification occurs by ER. Eg – In liver cell, detoxification of prussic acid occurs. ATP synthesis : - ER membranes are the sites of ATP synthesis. Between cell membrane and nucleus genetic material transportation occurs by ER.

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