Movement of Larger Molecules Across Membranes: Phagocytosis

00:01 So, that's been potocytosis and pinocytosis, cell drinking.

00:05 Next up is phagocytosis.

00:08 And phagocytosis is generally done only by specialized phagocytes or cells that eat.

00:14 To a limited extend, every cell has the capacity to eat relatively small things.

00:20 And we will talk about subsequently, eating apoptotic bodies.

00:25 Small, little buds that come off in apoptotic or cell that is dying due to program cell death.

00:33 So, phagocytosis will be a lot of cells.

00:35 But mainly, it's macrophages and neutrophils that do the major job of eating the large things like bacteria.

00:42 They will internalize it, not using clathrin and not using caveolin, but by a different pathway, and they will engulf that large thing in membrane, internalize it, turn it into a phagosome, and then they will fuse that with a lysosome where then, proteases and other mediators can cause the degradation of whatever has been ingested.

01:07 This is just a pseudo-colorized scanning electron micrograph of a neutrophil.

01:13 They are in yellow, that's eating a Bacillus anthracis, a bacteria.

01:19 One of the forms of bacteria. This is one that actually causes anthrax.

01:22 So, you can see that it -- you can actually eat something that's substantially larger than you are under appropriate circumstances.