Active Transport

• Active Transport

  • It is the movement of substances from areas of low concentration to high concentration. This requires energy (ATP).
  • Ion pumps are special carrier proteins that change shape to force ions across the membrane against the concentration gradient. Cellular energy (ATP) is required.

  
• There are two types of Active Transport

  1. Endocytosis
  2. Exocytosis
• Active Transport - Endocytosis

  • Materials that are too large to diffuse through the membrane or be transported through the membrane proteins, are engulfed within the cell membrane.
  • The membrane encloses the material in a vesicle (small membrane bubble) inside the cell and then separates from the main cell membrane.
• In Endocytosis


  There are two ways Endocytosis works:

  1. Phagocytosis: The ingestion of solids into a cell through endocytosis.
  2. Pinocytosis: The ingestion of fluids into a cell through endocytosis.

  
• Exocytosis


  • It occurs when substances inside of the cell are secreted out of the cell through a vesicle fusing with the cell membrane.
  • Cells that frequently secrete materials often have lots of vesicles (and a large golgi body).