Explain protein transport plz

[hephzi]

explain the role of the rough endoplasmic reticulum (RER) and the Golgi apparatus in protein transport within cells and including its role in formation of extracellular enzymes

i always struggle with this question and i am doing as level biology, can anyone explain me this simply and not to scientific plz

[kolean]

Rough ER means that ribosomes are attached to the ER. Ribosomes are what takes the mRNA and translates it into proteins/enzymes.

If the protein is bound for the outside (extracellular) or even if it can not touch the cell's own cytoplasm, then the protein will be made and placed inside the ER.
Inside the ER, the newly made protein/enzyme will bud off from the ER's membrane forming its own secretory membrane around it to keep it from being exposed to the cytoplasm. This secretory vesicle then travels to the Golgi apparatus.
The vesicle's membrane then merges with the Golgi's membrane, letting the protein/enzyme be safe once again in a membrane bound organelle.
Once inside the Golgi apparatus, the newly formed protein/enyzme will have its final modifications (glycosylation usually) that will then let the modified protein/enzyme bud off from the Golgi's membrane so that it is in its own membrane bound secretory vesicle once more, on its way -
to the outside of the cell for extracellular proteins (exocytosis),
or incorporation of receptor proteins into the cell's plasma membrane itself (vesicle's membrane intergrates into the cell's plasma membrane),
or even incorporation into the cell's organelles (into the organelle's cellular membrane or even into organelle's cytoplasm).

[hephzi]

thanks, this was very helpful