Golgi apparatus originating

How the Golgi apparatus maintains its polarized structure while molecules move from one compartment to another is still a matter of debate. Two models were originally proposed based on different experimental evidence (Fig. 9-5) the vesicular transport model and the cisternal maturation model. A third model known as the dual transport model combines elements from both vesicular transport and cisternal maturation models and can better explain intra-Golgi transport. 

Most organelle membranes, such as the tonoplast (6) and the Golgi apparatus (7), can be separated by density gradient ultracentrifugation of plant cell homogenates. However, other effective methods for the isolation of the plasma membrane (8,9) have been described. Moreover, another method that uses an aqueous two-phase system for the isolation of ER is also described (10). Those interested in these details for these methods should consult the original articles. 

Manton, I., Leedale, G. F. Observations on the fine structure of Paraphysomonas vestita, with special reference to the Golgi apparatus and the origin of scales. Phycologia 1, 37 (1961)... 

In an attempt to gain further insight into the origin of the milk lipid globule membrane, the composition of this membrane has been compared to that of secretory vesicle membranes (Keenan et al. 1979). The vesicle membrane was found to be compositionally intermediate between Golgi apparatus membranes and lipid globule membrane. However, the isolation procedure yielded a fraction enriched in immature secretory vesicles and mature secretory vesicles may more closely resemble lipid globule membrane in composition. 

The same could be true for molluscs, except that here calcification started at an earlier geologic age. From what we have presented about the mechanism of calcium carbonate deposition and its close association with the activities of the Golgi apparatus, one cannot escape the conclusion that the whole operation was originally conceived only for the rapid and efficient removal of calcium and perhaps some other elements from within the cell. The unique role of calcium in so many physiological activities307 must also allow for a valve system for the discharge of unwanted surplus. Mineralization probably started as an accident but once a reality it became explored by the organisms. 

The distal cytoplasm contains an abundance of granules, membrane-bound vesicles and mitochondria (Fig. 2.1). The majority of vesicles and granules appear to have their origin in the Golgi apparatus of the tegumental cytons, from where they are passed to the distal cytoplasm. These granules probably play a major role in the formation and replace-... 

These results of Hopp et al. (1978) constitute very strong evidence for the proposition that cellulose originates as a glucoprotein, at least in Prototheca. Hopp etal. (1978) have also shown that this alga makes dolichols of 90-105 carbon atoms, mostly as the C95 and Cioo forms from mevalonic acid. Synthesis mostly takes place in the mitochondria and Golgi apparatus. The evidence for a similar set of transfers in higher plants is slightly less firmly proven. 

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