Active transport

• Active transport is the movement of molecules or ions into or out of a cell from a region of low concentration to a region of high concentration using energy released from the hydrolysis of ATP and carrier proteins
• Active transport

  • relies on the use of carrier proteins
  • requires ATP
  • carrier protein is linked to ATp hydrolase
  • carrier changes shape and molecule is released on the other side
  • phosphate recombines with ADP to form ATP, catalysed by the enzyme ATP synthase
• Sodium-potassium pump is a type of ATP-driven pump

  • 3 sodium ions bind
  • ATP hydrolysed
  • Carrier protein changes shape and 3 sodium ions released outside cell
  • 2 potassium ions bind
  • Phosphate released
  • Carrier protein changes shape back and 2 potassium ions released inside cell
• Bulk transport occurs when substances larger than the membrane proteins are transported across the membrane
• Bulk transport required energy from the hydrolysis of ATP
• Exocytosis = fusion of vesicles with the cell surface membrane
• Endocytosis = formation of new vesicle within the cytoplasm