Active transport

Active Transport is: "the movement of molecules or ions into or out of a cell from a region of lower concentration to a higher concentration using ATP and carrier proteins"

In active transport ATP is used to:

• directly move molecules
• individually move molecules using a concentration gradient which has already been set up by direct active transport. This is known as co-transport.

It differs from passive forms of transport in the following ways:

• Metabolic energy in the form of ATP is needed
• substances are moved against a concentration gradient, that is from a lower to a higher concentration.
• Carrier protein moloecules which act as 'pumps' are involved.
• The process is very selective, with specific substances being transported.

Direct active transport of a single molecule or ion is described below:

• The carrier proteins span the plasma membrane and bind to the molecule or ion to be transported on one side of it.
• The molecule…