What is active transport?

When a cell expends energy to move molecules or ions across a membane, the process is known as active transport.
Active transport is when it takes energy for the cell to take something else in.

Active transport can be split into two categories:

1. Transport by Proteins

  • Membrane integral proteins can either act as channels, or as "flip-flop" pimps which move large or charged molecules across. Example: Na and K ions: Na/K pumps

2. Transport by Vesicles

  • due to the fluid nature of the membrane, vesicles can fuse with the plasma membrane and transport substances across it
  • Endocytosis: transport into cells. a. pinocytosis (drinking) b. phagocytosis (eating)
  • Exocytosis: transport out of cells. Important in types of cells which secrete specialized products like hormones (example : insuline)
Active transport is the movement of molecules across a cell membrane. This is in the direction against their concentration gradient.