Active Transport

• Define Active Transport

  The transportation of particles across the membrane, against their concentration gradient
• Active transport always requires ATP from respiration and a transport protein
• Inside the cell, there's lots of particles, while outside the cell, there's only a few particles

  This means that there is a steep concentration gradient
• • A molecule of ATP contains three phosphate ions
  • During active transport, a molecule of ATP is hydrolysed into a molecule of ADP and inorganic phosphate ions
  • The release of the phosphate ions causes the protein to revert to its original shape
• Process in active transport of one particle through membrane

  1. The desirable particle and a molecule of ATP bind to their respective binding sites on the transport protein in the membrane
  2. ATP is hydrolysed to ADP and a phosphate ion, transferring energy to the transport protein and triggering it to change shape
  3. This forces the particle through the protein and across the membrane
  4. The phosphate ion is releases, causing the protein to revert to its original shape
• Describe the co-transport of two particles across a membrane against their concentration gradients

  1. a transport protein binds the first particle and a molecule of ATP
  2. The transport protein hydrolyses ATP into ADP and a phosphate ion, causing the transport protein to change shape, forcing the first particle across the membrane
  3. The shape change reveals a second binding site in the protein, to which the second particle binds
  4. The phosphate ion is released, triggering the protein to revert to its original shape
  5. This forces the second particle across the membrane in the opposite direction