Membrane Transport, Endo/Exocytosis, Pino/Phagocytosis

Endocytosis

A mechanism by which large particles and macromolecules enter cells. "Into the cell."

Exocytosis

A mechanism by which substances move from the cytoplasm to the outside of the cell. "Out of the cell."

Active Transport

Integral proteins moving molecules across the plasma membrane against their concentration gradient. This process requires the use of energy.

Simple Diffusion

Small, uncharged molecules, such as oxygen, carbon dioxide, and fat-soluble molecules, can pass freely through the lipid bilayer of the plasma membrane through this process. A substance passes through a membrane without the aid of an intermediary such as a integral membrane protein.

Osmosis

The diffusion of water molecules across a membrane. Molecules in a solution tend to move down their concentration gradient; that is, the molecules move from a region where they are more concentrated to a region where they are less concentrated.

Phagocytosis

The ingestion of bacteria or other material by phagocytes and amoeboid protozoans. "Cell eating."

Pinocytosis

The ingestion of liquid into a cell by the budding of small vesicles from the cell membrane. "Cell drinking."

Facilitated Diffusion

The process of spontaneous passive transport of molecules or ions across a biological membrane via specific transmembrane integral proteins.