Bulk Transport

In addition to moving small ions and molecules through the membrane, cells also need to remove and take in larger molecules and particles (see Table for examples). Some cells are even capable of engulfing entire unicellular microorganisms. You might have correctly hypothesized that when a cell uptakes and releases large particles, it requires energy. A large particle, however, cannot pass through the membrane, even with energy that the cell supplies.

1 of 6