The Golgi apparatus is primarily made of a stack of flattened, membrane-bound sacs called cisternae, along with associated vesicles.
Here's a more detailed breakdown:
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Cisternae: These are the defining structural feature of the Golgi apparatus. They are flattened, disc-shaped sacs that are stacked on top of each other. Each stack typically contains 3-8 cisternae, although the number can vary. The space within a cisterna is called the lumen.
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Vesicles: These are small, membrane-bound sacs that bud off from the cisternae. Vesicles play a critical role in transporting proteins and lipids to, through, and from the Golgi apparatus. Different types of vesicles exist with specific functions.
The Golgi apparatus exhibits distinct polarity:
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Cis face (or cis-Golgi network - CGN): This is the "entry" face of the Golgi apparatus, closest to the endoplasmic reticulum (ER). It receives vesicles containing proteins and lipids from the ER.
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Trans face (or trans-Golgi network - TGN): This is the "exit" face of the Golgi apparatus. From here, vesicles bud off and transport processed proteins and lipids to their final destinations, such as lysosomes, the plasma membrane, or secretion outside the cell.
The Golgi apparatus is a dynamic organelle, constantly receiving, modifying, and packaging molecules. This complex process relies on its unique structural components and their interactions.
