The organelle that packages proteins, e.g., the hormone, insulin, into secretory vesicles and distributes them by exocytosis out of the cell is: smooth ER nucleolus lysosome Rough ER golgi complex
The Correct Answer and Explanation is:
The correct answer is the Golgi complex (also known as the Golgi apparatus).
Explanation:
The Golgi complex is a membrane-bound organelle that plays a critical role in modifying, sorting, and packaging proteins and lipids for delivery to specific destinations, both inside and outside the cell. It consists of a series of stacked, flattened membranes, called cisternae, which are involved in the processing of proteins received from the endoplasmic reticulum (ER).
Here’s a breakdown of its key functions:
- Protein Processing: Proteins synthesized in the rough endoplasmic reticulum (ER) are transported in vesicles to the Golgi complex. Once inside, they undergo further modifications, such as glycosylation (addition of carbohydrate chains) or phosphorylation, which are essential for their final function.
- Sorting and Packaging: After modification, the proteins are sorted and packaged into secretory vesicles, which are then directed toward their appropriate destinations. This includes secretion outside the cell, delivery to the cell membrane, or transportation to other organelles.
- Exocytosis: One of the major roles of the Golgi complex is the packaging of proteins, like hormones (e.g., insulin), into vesicles for exocytosis. Exocytosis is the process by which these vesicles fuse with the plasma membrane, releasing their contents outside the cell. This is particularly important for hormone secretion, where insulin, for example, is released into the bloodstream from pancreatic cells.
Why not the others?
- Smooth ER: While the smooth ER synthesizes lipids and detoxifies chemicals, it does not play a role in the packaging or secretion of proteins.
- Nucleolus: The nucleolus is involved in the production of ribosomes and is not involved in protein packaging.
- Lysosome: Lysosomes contain digestive enzymes and are involved in breaking down cellular waste, not in protein secretion.
- Rough ER: The rough ER is where proteins are synthesized, but it is the Golgi complex that modifies and packages them for secretion.
In conclusion, the Golgi complex is essential for processing and packaging proteins for secretion outside the cell, such as in the case of insulin release.
