What are some examples of situations where a cell might use phagocytosis or exocytosis?
Phagocytosis and endocytosis are two different cellular mechanisms.
Phagocytosis is the process by which a cell takes in material, to neutralize a threat, obtain nourishment, or absorb information.
i. Metazoan (multicellular organisms) immune system is based on the recognition and ingestion of harmful bacteria viruses or protists.
ii. Protozoan (single cell organisms) use phagocytosis to get food.
iii. Horizontal Gene Transfer is the process by which many protists
maintain virulence in the face of human developed pesticides.
Genes of one kind of bacterium are passed on to another (laterally and not vertically as from parent to offspring) to confer antibiotic resistance.
Exocytosis is a process in which a cell transports molecules (such as proteins) out of the cell by expelling them in an energy-using process. Exocytosis and its counterpart, endocytosis, are used by all cells because most chemical substances important to them are large polar molecules that cannot pass through the hydrophobic portion of the cell membrane by passive means.
i. In the human body, proteins made in a cell are passed out to be carried by the blood to another part of the body.
ii. In a large tree,glucose made in plant leaf cells is transported to roots, stems and storage organs of the tree.