Active Transport: involves the use of cell energy to move materials accross a cell membrane against the concentration gradient.

Concentration Gradient: a difference in the number of molecules or ions of a substance between adjoining regions. Without the addition of energy, molecules tend to diffuse from the area of higher concentration to the area of lower concentration.



Endocytosis: the process by which cells ingest materials

Exocytosis: is the process by which large molecules held within the cell are transported to the externalenviroment

Two Types of Endocytosis

Pinocytosis a forms of endocytosis in which liquid droplets are englufed by cells.

Phagocytosis a forms of endocytosis in which solid particles are engulfed by cells.

Endocytosis and Exocytosis

Cells also use energy to transfer material in bulk. But this time by forming membranous sacs that hold their contents under wraps in a process called endocytosis. Part of the surface membrane encloses the cells interior in the opposite process called exocytosis. The sac moves through the cytoplasm to the membrane, fuses with it, then releases the contents

Active Transport Using a Pore

In this case the cell uses transport proteins which need a boost from an energy molecule. This actually changes the shape of the proteins causing them to pump different molecules and ion across the membrane. Now from the side with fewer solutes to the side with more.