Endo/exocytosis

• Endocytosis is bulk transport of substances into the cell. It uses ATP to move the membrane to form vesicles to contain substance as it enters cell. 
• Endocytosis:

  • Bulk movement of material into the cell 
  • Membrane engulfs the material 
  • Membrane fuses together 
  • Vesicle is formed 
  • ATP required. 
• Exocytosis is the bulk transport of substances out of the cell. It uses ATP to move the vesicle and allow it to fuse with membrane to allow the substance to leave the cell. 
• Exocytosis:

  • Bulk movement of material out of the cell 
  • Vesicle fuses with the membrane. 
  • Substances moved out of the cell 
  • ATP required. 
• Endocytosis and exocytosis are both active processes.
• An example of bulk transport is hormones. Pancreatic cells make and package insulin into vesicles in the Golgi apparatus. When the vesicles fuse with the membrane the insulin is released into the blood stream. 
• An example of bulk transport is white blood cells . Microorganisms are engulfed by forming a vesicle around them and then allowing the vesicle to fuse with a lysosome in the white blood cell to allow digestion of the micro-organism (phagocytosis).