GOLGI Appartus... is an organelle mainly devoted to processing the proteins made in the E.R., via glycosylation, i.e., adding sugar molecules to form glycoproteins, which can end up as embedded integral membrane proteins. Other proteins moving through the Golgi will end up in lysosomes or may be secreted by exocytosis (e.g., digestive enzymes). In mucus-secreting cells of the epithelia, the amount of carbohydrate far exceeds the protein amounts, thus mucopolysaccharides. In plant cells, the Golgi secretes the cell plate & cell wall. The Golgi also cut up large precursor proteins into small peptide fragments (ex: hormones & neurotransmitters as pro-opiomelanocortin - a 265 amino acid polypeptide from which are cut the following: ACTH , alpha & beta MSH, & beta-endorphin.
Golgi consists of a stack of membrane-bound cisternae located between the endoplasmic reticulum and the cell surface divided into 3 areas:
a) CIS-Golgi- accepts transport vesicles (via microtubules from ER) (phosprylation here)
b) MEDIAL-Golgi - glycolyslation occurs here adding sugars as mannose & galactose
c) TRANS-Golgi sorts the products and packages them (e.g., lysosomes).
Camillo Golgi                Knightley Images of the Golgi