ENDOPLASMIC RETICULUM STRUCTURE AND FUNCTIONS

Endoplasmic Reticulum is a complex network of tubular membranes exclusively present in the cytoplasm of the eukaryotic cell.This topic covers History,Structure,Types and functions of Endoplasmic reticulum

1. ENDOPLASMIC RETICULUM

2. ENDOPLASMIC RETICULUM Largest single membrane bound intracellular compartment Light microscope -filamentous -basophilic in staining- Ergastoplasm Porter and kallman in 1953 -“endoplasmic reticulum”. +All eukaryotic cells -Eggs, Embryonic cells,RBC,Bacteria . Dr.Ravirala Naresh,Asst. Professor

3. MORPHOLOGY Three forms Cisternae Vesicles Tubules Dr.Ravirala Naresh,Asst. Professor

4. CISTERNAE Long flattened sac like Unbranched Parallel in bundles Diameter40-50µm + Ribosomes –Surface ↑Actively busy in protein synthesis- licer,pancreas and brain Dr.Ravirala Naresh,Asst. Professor

5. VESICLES Oval,membrane bound 40-500µm ↑ Pancreatic cells Found end of cisternae and tubules Many free in cytoplasm Dr.Ravirala Naresh,Asst. Professor

6. TUBULES Branched- forms Reticular system 50-100µm Non secretory cells-Striated muscle Dr.Ravirala Naresh,Asst. Professor

7. ENZYMES OF ER Stearases NADH- cytochrome C reductase NADH- diaphorase Glucose-6-phosphatase Glycosyl transferase Mg ++  activated atpase . Dr.Ravirala Naresh,Asst. Professor

8. TYPES OF ER + & - Ribosomes Granular/Rough ER/RER A granular/Smooth ER/SER Dr.Ravirala Naresh,Asst. Professor

9. RER Ribosomes –surface Ergastoplasm / Basiophilic bodies/ Chromophilic / Nissl bodies ↑ Active in protein synthesis-Pancreatic cells,Plasma cells,Goblet cells,liver cells. Mainly of cisternae Dr.Ravirala Naresh,Asst. Professor

10. SER - Ribosomes ↑ Inactive in protein synthesis ↑ Lipid &glycogen Adipose cells,Glycogen storing cells Muscle cells- Sarcoplasmic reticulum Retinal cells-myeloid bodies Dr.Ravirala Naresh,Asst. Professor

11. FUNCTIONS Structural skeletal framework-Cytoskeleton Transport material Exchange between cytoplasm & nucleus Forms nuclear membrane Protein synthesis-RER Lipids & lipoproteins-SER Transmit impulses-SER Release of calcium—SER Synthesis of steroid hormones-SER- testis,ovary Detoxification-SER-Liver Dr.Ravirala Naresh,Asst. Professor