Active Transport

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  • Created by: zoolouise
  • Created on: 20-04-16 11:28

Active Transport

  • Active transport - the movement of moleules or ions into or out of a cell from a region of lower concentration to a region of higher concentration using energy and carrier proteins

Active transport allows cells to exchange molecules against a concentration gradient, metabolic energy is required for this. Once inside the molecules are prevented from leaking back out by the barrier of the cell surface membrane's bi-layer. This means a different environment is maintained on either side of the membrane.

Active transport is different from passive forms of transport in the following ways:

  • Metabolic energy in the form of ATP is needed
  • Materials are moved against a concentration gradient, i.e. from lower to higher
  • Carrier protein molecules which act as 'pumps' are involved
  • The process is very selective, with specific substances being transpored. The carrier proteins accept the molecule to be moved and the molecule enters the cell as a result of a change in shape of the carrier protein

Active transport uses ATP in one of two ways:

  • By using ATP directly to move molecules
  • By using a concentration gradient that has already been set up by direct active transport. Also known as co-transport.

Direct active transport of a single molecule or ion:

  • Carrier proteins span the cell-surface membrane and accept the molecules or ions to be transported on one side of it
  • The molecules or ions bind to receptors on the channels of the carrier…


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