Active Transport (Cellular Transport)

• Active transport:

  Moves substances from a more dilute solution to a more concentrated solution (against the concentration gradient).
• This requires energy from respiration. In active Transport, the particles are moved against the concentration gradient. Also it does requires energy from respiration.
• An example of active transport in cells:

  
• An example of active transport in plants:

  
• Diffusion and osmosis rely upon the passive (no energy is required) transport of substances down concentration gradients.

  • Cells also need to be able to transport substances across the cell membrane against a concentration gradient.
  • This requires the input of energy (in the form of ATP) released from cellular respiration.
  • Active transport moves substances from a more dilute solution to a more concentrated solution.
• Active transport across the cell membrane involves protein carrier molecules embedded in the cell membrane:

  
• Plants:

  • Root hair cells lining the surface of plant roots need to move minerals such as magnesium ions from a region of lower concentration (the very dilute solution of minerals in the soil surrounding the roots) to a region of higher concentration (inside the cytoplasm of the cell).
  • Mineral ions are needed by plants to function healthily.
  • Magnesium ions are needed to make chlorophyll.
  • Nitrate ions are needed to make amino acids and therefore for protein synthesis (and subsequently growth).
• Animals (part 1):

  • Nutrients (e.g. glucose) can diffuse into the bloodstream from the small intestine (the gut).
  • But this is dependent on a concentration gradient existing between the small intestine and the bloodstream.
  • i.e. a higher concentration of glucose in the small intestine compared to the bloodstream.
• Animals (part 2):

  Active transport allows nutrients like glucose to be transported into the bloodstream from the small intestine even when the concentration gradient is in the wrong direction.

  • i.e. when the concentration of sugar molecules in the bloodstream is higher.
  • This is essential to stop us from starving as glucose can continuously be transported to the bloodstream.
• How can a cell bring these molecules in, to do this the cell uses a process called active transport. Like this...