Here's why:
* ER Synthesis: The endoplasmic reticulum (ER) is the site of synthesis for many proteins and lipids.
* Golgi Processing: The Golgi apparatus acts like a cellular "post office," receiving proteins and lipids from the ER. It then modifies, sorts, and packages them for their final destinations.
* Modifications: The Golgi apparatus performs various modifications on the ER-synthesized molecules, including:
* Glycosylation: Adding sugar chains (glycans) to proteins.
* Phosphorylation: Adding phosphate groups to proteins.
* Sulfation: Adding sulfate groups to proteins.
* Lipid modifications: Modifying and processing lipids.
In essence, the Golgi apparatus further refines and prepares proteins and lipids for their specific functions within the cell or for secretion outside the cell.
