active transport

• Active transport


  Moves substances from a more dilute solution to a more concentrated solution, requires the input of energy (in the form of ATP) released from cellular respiration
• Diffusion and osmosis rely upon the passive (no energy is required) transport of substances down concentration gradients
• Cells need to be able to transport substances across the cell membrane against a concentration gradient
• Active transport


  • 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)
• Animals


  • 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. 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)
• Active transport is essential to stop us from starving as glucose can continuously be transported to the bloodstream
• Difference between active transport and diffusion

  Active transport requires energy, whereas diffusion is a passive process