structure and function of golgi apparatus Flashcards
What is the structure of the Golgi apparatus?
The Golgi apparatus is a stack of membrane-bound cisternae that processes and modifies polypeptides produced in the rough endoplasmic reticulum (RER).
What is the primary function of the Golgi apparatus?
The primary function of the Golgi apparatus is to process and modify polypeptides made in the RER, such as adding carbohydrates to form glycoproteins or assembling polypeptides into quaternary protein structures.
How are proteins processed in the Golgi apparatus?
- Enzymes in the cisternae modify proteins, e.g., by adding carbohydrate groups.
- Polypeptides may also be assembled into quaternary structures.
- The processing is sequential, with proteins gradually moving from the cis side (nearest RER) to the trans side of the Golgi apparatus.
How are proteins transported from the Golgi apparatus to their destinations?
After processing is complete, proteins are packaged into vesicles and transported to their destinations, which could include:
- Lysosomes
- Food vacuoles
- Cell surface membranes (for secretion)
What are the two models that explain how proteins move through the Golgi apparatus?
- Vesicle transport model: The cisternae remain stationary, and proteins are transported between them by vesicles.
- Cisternal maturation model: Vesicles from the RER fuse to form new cisternae on the cis side of the Golgi, which then gradually mature and move through the Golgi until they reach the trans side, where they break up into vesicles.
Which model of Golgi apparatus function has stronger evidence?
The cisternal maturation model has stronger evidence at present, though there are still many questions about the function and the arrangement of the cisternae.
What modifications can be made to proteins in the Golgi apparatus?
The Golgi apparatus can modify proteins by:
- Glycosylation (adding carbohydrate groups to form glycoproteins)
- Assembling quaternary protein structures (combining polypeptides with other subunits).
