Golgi Apparatus
The golgi apparatus are stacks of flattened hollow membranous sacs. On a diagram, they somewhat resemble pancakes. Each sac is called a cisterna (plural: cisternae); human cells usually have about 5 cisternae in a single stack. A cell may have dozens of stacks, which contain enzymes which process and modify proteins as they travel through the organelle.
The golgi has two sides - the cis face and the trans face: The cis face receives proteins from the ER and passes them down the golgi. This is usually the face closest to the ER. The trans face sends off the modified proteins by packaging them in small vesicles. These vesicles are then sent off to where they are needed (they can even be sent outside the cell). The destination is specified by using enzymes to change the surface molecules of proteins. It's just like "tagging" a product with its destination. The golgi can also synthesize hyaluronic acid, which helps stick animal cells together. |