| How was Golgi apparatus discovered? | late 19th century, Camilio Golgi was manipulating nerve cells, where he discovered using specific dyes the Golgi body, which he then identified in other eukaryotic cells |
| Talk about Golgi body composition. | Several flattened, disk-like cisternae with detailed rims and associated vesicles and tubules. |
| What are cisternae? | Curved and arranged in orderly stack resembling a shallow bowl. Each stack is called dictyosome and comprises several cisternae in animal cells and almost 20 in plant cells, their number is variable according to cell.
Golgi body may include one single dictyosome or up to several thousands depending on cell type and physiology. Dictyosome are not cell independent rather they are interconnected through tubules and work coordinately. Golgi is part of endomembrane system. |
| Talk about the structure of the dictyosome. | Divided functionally into distinct compartments. Cis-cisternae (convex) face differ from Trans-cisternae (concave face) differ from middle one.
Each compartment has specific enzymes involved in synthesis and maturation of cell components (glycoproteins, glycolipids and polysaccharides) .In addition to wall delimited cisternae, there are tubular networks at both cis and trans side. cis-Golgi network and trans-Golgi network, play a key role in sorting of molecules (CGN sorts molecules that need to go back to RER from those that continue their export to cis. TGN segregates proteins into different vesicles directed to the diverse cell compartments. |
| Are Golgi body mobile? | Flux movement vesicles are continuously added by fusion with cis face and other are detached from trans face and edges of other cisternae. |
| Talk about Golgi role in glycosylation. | Assembly of sugar motifs to protein is started in RER and continued in Golgi. Sugar motifs resulting from N-glycosylation in Golgi are matured by adding and removing monosaccharides catalyzed by different enzymes and different cisternae, Also Golgi plays a role in O-glycosylation, sugar motif is connected to polar OH side chain of aa (serine or threonine). Glycosylation is necessary for protein maturation and folding and targeting destinations. This is in addition to lipid glycosylation (BG) |
| Talk about polysaccharide synthesis role of Golgi apparatus. | most complex ones are produced in Golgi, GAGs of ECM are produced and released by exocytosis. Hemicellulose and pectin of plant cell walls are as well the product of Golgi. Golgi numbers increase in plant cells during division because of their role in cell wall production. |
| Talk about the mechanism of cell wall synthesis role played by Golgi. | vesicles migrate due to microtubules of phragmoplast toward equatorial plate during cytokinesis. These vesicles contain cell wall material fuse together to form a plate that grows toward old cell wall by fusion of additional vesicles. Finally, edges fuse with ancient cell wall separating the two cells, this cell wall requires maturation by addition (cellulose) in situ (cellulose synthesaze enzyme) |
| Talk about the sorting role of Golgi. | They are well developed in cells involved in active secretion (goblet cells) since secretory products are matured. sorted and packed in them, They are also responsible for lysosome preparation , therefore there are different types of vesicles that bud or merge with cisternal membranes, some are coated, which helps sorting and targeting vesicles.
These packed proteins packed in vesicles are packed depending on final destination (address code). |
| Talk about Golgi role in proliferation of cell membranes. | Sorting of proteins, destined to be secreted to target organelles, which is done in vesicles surrounded by membranes detached from edges of middle cisternae and trans cisternae. This process causes membrane proliferation of targeted membrane. |
