Active transport uses energy to move molecules against a concentration gradient

This energy may either be generated by: 

• The direct hydrolysis of ATP (primary active transport)
  

• Indirectly coupling transport with another molecule that is moving along its gradient (secondary active transport)
  

Active transport involves the use of membrane proteins (called protein pumps due to their use of energy)

• A specific solute will bind to the protein pump on one side of the membrane
  

• The hydrolysis of ATP (to ADP + Pi) causes a conformational change in the protein pump
  

• The solute molecule is consequently translocated across the membrane (against the gradient) and released
  

Primary Active Transport