- Taking in of solid substances by invagination of the cell surface membrane (eg. amoeba taking in food particles)
- Sequence of events
1. A small portion of the cell surface membrane invaginates to enclose the solid particles.
2. The particle is packaged within a membrane-enclosed sac that can be large enough to be called a vacuole.
3. Phagocytic vacuole pinches off from the cell surface membrane.
4. Cell surface membrane reforms
- Taking in of liquid and soluble materials by invagination of the cell surface membrane
1. A small portion of the cell surface membrane invaginates to enclose the liquid and soluble materials
2. The particle is packaged within a membrane-enclosed sac called pinocytotic vesicle.
- Taking in of specific substances irregardless of the low concentration in the extracellular fluid
- When the specific substances also known as ligands bind to the receptor sites of receptor proteins they trigger the invagination of the cell surface membrane.
- This results in the formation of coated vesicle that contain specific ligand molecules
- After the ligands are taken up by the cell, the receptors are brought back to the cell surface membrane by the same vesicle.