[Cell Transport Menu]

Cell Transport

Movement of Materials In & Out of Cells

Processes that cells use to move molecules across their membranes are:

Passive Transport: Movement of molecules from high to low concentration, using no energy.

A. Diffusion- Does not use energy.

B. Osmosis- Does not use energy.

C. Facilitated Diffusion- Does not use energy. Membranes in the cell membrane pick up molecules & carry them across the membrane from high to low concentration. (Animation)

The Following are Energy Requiring Processes:

D. Active Transport: A way cells get needed materials by using energy to move materials against a concentration gradient (molecules are moved from low to high concentration (against diffusion)).

Active Transport is used in movement, breathing, digestion, thinking, etc..

E. Endocytosis: (Endo - means to bring in) Energy requiring process where cell membrane surrounds molecules, forming a pocket which becomes a vacuole in the cytoplasm. (Animation)

Types of Endocytosis:

a) Phagocytosis: Membrane surrounds large particles, forms a pocket, then vacuole. This is how an amoeba or white blood cell feeds. (Animation)

b) Pinocytosis: Literally means cell drinking. Membrane surrounds a liquid, forms a pocket, then a vacuole.


F. Exocytosis: (Exo - means to take out) Energy requiring process where a vacuole containing large molecules joins with the membrane, makes an opening, and squeezes the molecules out of the cell. (Animation) (Animation)