1

Bulk TransportWhen molecules are too large to move through a

channel protein or by using a carrier protein, vesicles are used to move the “bulk” molecule.

Bulk transport of substances is accomplished by

1. endocytosis – movement of substances into the cell

2. exocytosis – movement of materials out of the cell

BOTH require energy from the cellB3, B2.1, B3.6

2

Endocytosis occurs when the plasma membrane envelops food particles and liquids into a vesicle to take into the cell

-3 types:

B3, B2.1, B3.6

3B3, B2.1, B3.6

1. Phagocytosis (cell-eating)– the cell takes in particulate matter

4B3, B2.1, B3.6

2. Pinocytosis (cell-drinking) – the cell takes in only fluid

5B3, B2.1, B3.6

3. Receptor-mediated endocytosis – specific molecules are taken in after they bind to a receptor

-the receptors are recycled for later use

6

Exocytosis occurs when material is discharged from the cell.

-vesicles in the cytoplasm fuse with the cell membrane and release their contents to the exterior of the cell

-used in animals to secrete hormones, neurotransmitters, digestive enzymes, etc

B3, B2.1, B3.6