Active Transport

Active Transport

1. Unlike Diffusion

   • Diffusion
   • Diffusion = High concentration to low concentration
     • Along a concentration gradient
   • Low concentration to high concentration
     • Against a concentration gradient

2. Used to transport dissolved molecules from a low concentration to a high concentration

   • Against the concentration gradient

3. Requires energy from respiration

4. Protein carriers

   • Responsible for carrying specific molecules through a cell membrane into a cell
   • Binding site, allows molecules to bind to outside of membrane
   • Energy from respiration changes the shape of the protein
     • Releases the substance onto the other side of the membrane

5. Examples from nature:

   • Root hair cells
     • Need to absorb ions (like nitrates) from soil for nutrients
   • Small intestine villi cells
     • Alongside diffusion, maximises absorption of glucose and other substances