Active transport

• Active transport: the net movement of particles from an area of low concentration to an area of high concentration, against the concentration gradient
• How ATP is used in active transport:

  • to directly move molecules
  • individually move molecules using a concentration gradient that has already been set up by active transport (co-transport)
• Process of active transport in the membrane:

  • carrier proteins bind to the molecule to be transported
  • the molecule binds to receptor sites on the carrier proteins
  • inside the cell, ATP binds to the protein causing it to split into ADP and an inorganic phosphate
  • this causes the protein molecule to change shape and open the the opposite side of the membrane
  • the molecule is released to the other side of the membrane
  • the protein reverts back to its original shape as the phoshate is released from the protein
• The sodium-potassium pump:

  • sodium ions are actively removed from the cell and potassium ions are actively transported in
  • used in nerve impulse transmission