Active and mass transport

• Movement of molecules against the concentration gradient- from low to high concentration. It needs specific carrier proteins and ATP.
• 1. Molecule binds to receptor sites on carrier protein.
  2. ATP binds to carrier protein- becomes ADP and the carrier protein changes shape.
  3. Shape change causes the protein to open.
  4. Molecule is released.
  5. Phosphate group is released.
• Mass transport is when large molecules (enzymes, hormones, whole cells) that are too big to move in and out of a cell by a channel or carrier protein.
• Endocytosis


  Substances are taken into a vesicle that is made of membrane.
• Exocytosis

  Substances excreted from vesicle.
• Mass transport requires energy.
• Movement of vesicles along the microtubule, changing shape of cell to engulf materials, fusion of cell membrane as vesicles form: requires energy.
• Endocytosis examples: pinocytosis(fluids) and phagocytosis(solid).