4.4 - Active transport

• Definition of active transport ?

  The movement of molecules or ions into or out of a cell from a region of lower conc. to a region of higher conc. using ATP and carrier proteins
• Where is the energy needed for active transport released from ?

  The hydrolysis of ATP
• 3 differences between active transport and passive forms of transport ?

  ATP is needed, Substances are moved against a conc. gradient, Carrier protein molecules that act as pumps are involved
• Describe how active transport occurs ?

  The molecule binds to receptor sites on the carrier protein as they are complementary, ATP binds to the protein on the inside of the cell and is hydrolysed to produce ADP and a phosphate, the energy released allows a conformational change to occur and the molecule is released into the cell, the phosphate molecule is released causing the protein to go back to its original shape
• An example where a molecule is moved out via AT whilst another moves in via AT ?

  Sodium-potassium pump