one key function of animal cells is to synthesise proteins for use inside the cell, to lead cell multiplication and for secretion out of cell, eg. insulin
1
proteins are synthesised, attached to the rough endoplasmic reticulum
2
newly synthesised proteins are transported through the cisternae of the rough ER and packaged into vesicles
3
they are transported to golgi apparatus, where vesicles fuse with the surface of the golgi apparatus and proteins enter
4
here the newly synthesised proteins are modified and then packaged into vesicles, secretory vesicles will transport proteins that are to be released from cell to cell surface membrane
5
they will fuse with membrane and release the protein by exocytosis
