Protein Production & Organelles
1) Proteins are made at the ribosomes.
2) The ribosomes attached to the rough endoplasmic reticulum (ER) make proteins that are attached to the cell membrane. The free ribosomes make proteins that stay in the cytoplasm.
3) At the rough ER proteins are folded and processed.
4) The proteins are then transported by vesicles from the rough ER to the Golgi Body.
5) At the Golgi Body, the proteins may have to have more processing.
6) The proteins will then enter vesicles again to be transported around the cell to where they're needed.
E.g. - glycoproteins found in mucus, are moved to the cell surface and secreted.
The cytoskeleton - a network of protein threads that run through the cytoplasm.
In eukaryotic cells, these protein threads are arranged as microfilaments (small solid strands) and microtubules (tiny protein cylinders).
The cytoskeleton has 4 main functions :
1) Microtubules & Microfilaments support the organelles, keeping them in position
2) M&M also help to strengthen the cell and maintain its shape
3) They're responsible for the transport of materials in the cell.
4) The proteins of the cytoskeleton can also cause the cell to move around.
E.g. The movement of cilia and flagella is caused by the cytoskeletal protein filaments that run through them. Single cells that have flagellum like sperm cells, will have the cytoskeleton propelling the whole cell.