Vesicles
Vesicles are sacs of membrane that bud off of the endomembrane system. These small compartments function as trucks to transport cargo. The cargo includes molecules such as proteins, large molecules that cannot pass through membranes, chemicals, and wastes. Vesicles are constant-forming structures that are made by the Golgi apparatus, the endoplasmic reticulum, and parts of the plasma membrane (Genetic Science Learning Center, 2000; Reece et al., 2011). The vesicle is wrapped by a coat of proteins when it is formed. The coat proteins select the cargo that is forming in the vesicle. As the chemicals accumulate within the vesicles, the edges increasingly swell. Once they reach a certain size the vesicle pinches off and releases the coat proteins. The vesicles deliver to structures within the cell and outside of the cell. Some deliver to structures within the cell to store the materials, and some fuse to the plasma membrane to be secreted outside the cell (Genetic Science Learning Center, 2000). |