STPM Biology Biological Molecules (Part 22)

Movement of Substances through Membrane 2

 

Active Transport

• Active transport = the movement of dissolved ions of molecules across the cell membrane, against the concentration gradient. Energy (ATP) is required.
• For examples,
• ions intake by root hairs of a plant.
• ions intake by sea weeds and algae.
• potassium ions uptake by red blood cells from blood plasma.

• Importance of active transport:
• enables cells to selectively absorb or expel molecules and ions.
• enables particles to move against the direction of the concentration gradient.
• allow cells to take in or expel ions or molecules at different rates.

• Active transport requires both carrier proteins and energy to transport molecules or ions. The mechanism of active transport is shown below:

Active transport