Transport By Vesicles

Transport by vesicles requires the cell to use metabolic energy (just like active transport mechanisms).

There two broad categories of transport by vesicles: endocytosis and exocytosis.

This video explains all types of transfer by vesicles. (Note: They mention a molecule called clathrin during receptor-mediated endocytosis. You don’t need to know about it.)

Endocytosis

During endocytosis, the plasma membrane pinches inward and take in substances into the cell.

There are three kinds of endocytosis:

Receptor-mediated endocytosis

0309 RMECredit

During receptor-mediated endocytosis, receptors on the surface of the plasma membrane bind to molecules outside of the cell. This triggers the cell to pinch inward (invaginate) and take the substance into the cell. Low-density lipoprotein (LDL) and HIV are two examples of something that enters the cell by receptor-mediated endocytosis.

Phagocytosis

Phagocytosis means “condition of the cell eating.” During phagocytosis, the cell pinches inward and engulfs the particle or microorganism. Two white blood cells that perform phagocytosis are neutrophils and macrophages. Watch these cells perform phagocytosis.
0309 PhagocytosisCredit

Pinocytosis

Pinocytosis is very similar to phagocytosis. The only difference is that during pinocytosis, the cell engulfs liquid and dissolved solutes that are outside of the cell.

0309 PinocytosisCredit

Exocytosis

During exocytosis, a vesicle leaves the Golgi apparatus and comes to the surface of the cell and releases something to outside the cell. Exocytosis is used to add new membrane material to the plasma membrane.
0310 ExocytosisCredit


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