Active Transport

Active transport (or active uptake) is the mediated transport of biochemicals, and other atomic/molecular substances, across membranes. Unlike passive transport, this process requires the expenditure of cellular energy to move molecules "uphill" against a gradient.

Process

In this form of transport, molecules move against either an electrical or concentration gradient (collectively termed an electrochemical gradient).

• The active transport of small molecules or ions across a cell membrane is generally carried out by transport proteins that are found in the membrane.

• Larger molecules such as starch can also be actively transported across the cell membrane by processes known as endocytosis and exocytosis.

• The process whereby particles are moved through a membrane from a region of low concentration to a region of high concentration is known as active transport