Answer
Bulk phase endocytosis seems to be a less specialized process than either phagocytosis or receptormediated endocytosis. Only a few types of cells are capable of phagocytosis ( e.g. macrophages and neutrophils), but most bodyl cells can carry out bulk phase endocytosis. Receptor-mediated endocytosis is also more specialized than bulk phase endocytosis: for the former process involves specific ligands and receptors while the latter does not. In phagocyosis the cell membrane develops pseudo pod which surround and eventually engulf solid material which is carried into the cytosol by vesicles pinched off from the cell membrane. Phagocytosis serves to get rid of pathogens an cell debris but also in the acquisition of nutrients. Formation of phagosomes and the action of lysosomes are involved in phagocytosis .
Work Step by Step
In bulk endocytosis, the plasma membrane fold in and take up extra cellular fluid and its content . A vesicle is pinched. The vesicle unites with a lysosome that secretes enzymes to digest the contents of the vesicle. These simpler substances are then transported to where they are needed. Absorptive cells and kidney cell employ this process. Receptor mediated endocytosis is very specialized involving plasma membrane receptors and ligands. Substances like Vitamin A and cobalamin are taken in by receptor mediated endocytosis which involves clathrin coated pits.
