ENDOPLASMIC RETICULUM The endoplasmic reticulum is an extensive network of flattened sheets, tubes, and sacs that are involved with two different functions inside the cell. The basic structure is a membrane that either contains ribosomes or doesn’t contain ribosomes. The rough endoplasmic reticulum or RER is the part of the ER that contains ribosomes, which are important in making proteins. The RER collectively forms a protein-making factory located near the nucleus. The smooth endoplasmic reticulum or SER does not contain ribosomes but makes other materials and aids in synthesis of lipids and hormones. From there, they can be used within the cell or exported outside of the cell.
GOLGI APPARATUS This is the part of the cell that packages the different cellular products made by the cell into vesicles that ultimately will leave the cell. It is the “post office” of the cell or the cell’s central
delivery system. It looks like a bunch off flattened sacks that modify and package the different proteins and lipids into spherical vesicles that migrate to the plasma membrane in order to leave the cell.
VACUOLES These are empty spaces inside the cell that form when endocytosis has occurred and parts of the plasma membrane are pinched off in the process.
LYSOSOMES These are sac-like vesicles that contain very strong degradative enzymes. They are made in the Golgi apparatus and act to destroy toxins and unwanted waste products or debris by merging with vesicles, destroying their contents. There are many different “lysosomal storage diseases” that happen because of a malfunction in the lysosomes, resulting in a buildup of a waste product. 13
