Movement - Active transport

• Movement of molecules or ions against a concentration gradient ( from low to high concentration)
• Requires energy via hydrolysis of ATP released in respiration and intrinsic carrier proteins in the membrane
• cells which perform a lot of active transport also have a lot of mitochondria
• Allows cells to get rid of unwanted substances even when the concentration outside is very high
• used in the sodium potassium pump in nerve cells to move Na+ and K+ ions against concentration gradient — this is important for nerve action