Active Transport (Cambridge (CIE) A Level Biology)

The Process of Active Transport

• Active transport is the movement of molecules and ions through a cell membrane from a region of lower concentration to a region of higher concentration using energy from respiration

• Active transport requires carrier proteins (each carrier protein being specific for a particular type of molecule or ion)

• Although facilitated diffusion also uses carrier protein, active transport is different as it requires an input of additional energy

• The energy is required to make the carrier protein change shape, allowing it to transfer the molecules or ions across the cell membrane

• The energy required is provided by hydrolysis of ATP (adenosine triphosphate), which is produced during respiration

Active Transport Diagram

A carrier protein changing shape during active transport

• Active transport is important in the following processes:

  • Reabsorption of useful molecules and ions into the blood after filtration into the kidney tubules

  • Absorption of some products of digestion from the digestive tract

  • Loading sugar from the photosynthesising cells of leaves into the phloem tissue for transport around the plant

  • Loading inorganic ions from the soil into root hairs