Golgi apparatus

Cell Biology

1. Golgi Apparatus By. Harshraj Subhash Shinde K. K. Wagh Agril. Biotechnology, Nashik

2. Outlines History/Discovery Other names Occurrence Morphology Biochemical properties Origin/Biogenesis Function-in plants and animals

3. Historical An Italian neurologist Camillo Golgi in 1873 discovered Golgi apparatus By reporting the existence of such an organelle inside cell, he raised a storm of controversy known as Golgi controversy

4. Other names Due to their high lipid contents, G olgi apparatuses were called lipochondria . Since originally these were known to be networks, they were also called “dictyosomes”. (Gr., dictyes=net) Also known as G olgi complex, Golgisome, G olgi bodies, G olgi material, Golgi membrane, etc Golgi apparatus of plants or lower invertebrates is usually referred to as G olgi body or dictyosome

5. Occurrence The Golgi apparatus occurs in all cells except the prokaryotic (viz., mycoplasmas, bacteria and blue green algae) and eukaryotic cells of certain fungi, sperm cells of bryophytes mature sperms or red blood cells of animals. One animal cell usually contain a single Golgi apparatus. But number vary from cell to cell and from animal to animal. N erve cells ,liver cell and oocytes have multiple Golgi apparatuses. Single algal cell contains 25,000 Golgi apparatuses

6. Morphology

7. Morphology The Golgi apparatus is morphologically very similar in both plant and animal cells Its shape and form vary from cell to cell Golgi apparatus appears as a complex array of interconnecting tubules, vesicles and cisternae Cisternae or flattened sac- Simplest unit of Golgi apparatus is cisterna. This is a membrane bound space in which various materials and secretions may occur. Numerous cisternae are associated and appear in a stack like. The group of cisternae is called the dictyosome and group of dictyosomes make up the cells Golgi apparatus

8. Cont.. b. Tubules- A complex array of associated vesicles and tubules (30-50nm in diameter) surround the dictyosome c. Vesicles- vesicles are of three types i) transitional vesicles- form as blebs from the transitional ER to Golgi ii) Secretory vesicles - occurs between Golgi and plasma membrane iii) Clathrin coated vesicles- plays role in intra-cellular traffic of membranes and secretory product's.

9. Biochemical properties of Golgi apparatus Glycosyl transferase and thiamine pyrophosphatase- Localized in the cisternae. Transferase enzymes are present in the membrane of G olgi apparatus Acid phosphatase- present in GERL region Golgi apparatus of animal cell contain following important enzymes- oxidoreductase, phospholipase, kinase, glycosyl transferases and glucotransferases

10. Origin Method of origin of Golgi apparatus is de novo formation Individual stacks of cisternae may arise from the pre-existing stacks by division or fragmentation Membrane of Golgi apparatus originates from the membrane of smooth endoplasmic reticulum Cells of dormant seeds of higher plants generally lack Golgi apparatuses

11. Functions Golgi vesicles are often , referred to as the “traffic police” of the cell. They play a key role in sorting many of the cells proteins and membrane constituents and in directing them to their proper destinations Golgi enzymes adds signal or tag such as carbohydrates or phosphate residues to certain proteins to direct them to their proper destination. In plants, Golgi apparatus is mainly involved in the secretion of materials of cell walls (lipids, glycoprotein, cellulose, hemicellulose and lignin) Involved in the cell plate and cell membrane formation of daughter cells.

12. Cont.. In animals Golgi apparatus is involved in the packaging and exocytosis of the i) Mucus (glycoprotein) ii) L actoprotein secretion by mammary glands iii) secretion of collagen iv) formation of melanin and other pigments It is also involved in the formation of cellular organelles like plasma membrane, lysosomes, acrosome of spermatozoa and granules of oocytes

13. Reference book Cell Biology, Genetics, Molecular Biology, Evolution and Ecology S.CHAND P.S . VERMA V.K.AGARWAL

14. --- organelle is known as traffic police of cell. Lysosome Golgi Nucleus Mitochondria