ENDOCYTOSIS
- Membrane invagination has solutes in it
- Vesicle formed from this invagination traffics to the early endosome
- Next the solutes are trafficked to the late endosome
- Solutes are then delivered to the lysosome where they are broken down for use by the cell
Early Endosome vs Late Endosome
- Differences in acidity (early endosome is slightly less acidic)
- Differences in protein composition
Three types of endocytosis:
1) Pinocytosis
- All eukaryotic cells utilize this
- Vesicles are less than 150nm in diameter
- Vesicles generally greater than 250nm in diameter (phagosomes)
- Phagosomes delivered directly to lysosomes
- Usually only specialized cells use phagocytosis
- All eukaryotic cells utilize this
- Very specific for the molecules ingested
- Can concentrate solute molecules
- Can allow for transcytosis
Transcytosis
- Allows polarized cells to move molecules from one side of the cell to another