Exocytosis and Endocytosis Flashcards
Two main types of endocytosis
differ according to the size of the endocytic vesicles formed. They are:
Phagocytosis and pinocytosis.
In phagocytosis
(“cell eating”), large particles are ingested via large vesicles called
phagosomes
In pinocytosis (“cell drinking”), fluid and solutes are ingested via small
pinocytic vesicles
Macrophages scavenge
senescent cells
Professional phagocytes in mammals are two classes of white blood cells:
macrophages and neutrophils
Phagocytosis is a _______ process.
triggered; requires activation of receptors that transmit signals to the cell interior and initiate the response
Pinocytosis is a _______ process.
constitutive; occurs continuously
Endocytotic pathway?
endocytosed vesicle ->
early endosome (low pH, dissociation of substrate from receptor) -> back to membrane or late endosome -> lysosome
What does clathrin do?
It is a large protein that assists in the formation of a coated pit on the inner surface of the plasma membrane of the cell.. This pit then buds into the cell to form a coated vesicle in the cytoplasm of the cell.
Exocytosis is the
fusion of the vesicles with the plasma membrane (which is made of phospholipid bilayer)
Two secretory pathways:
constitutive and regulated
Three pathways of protein sorting in the trans Golgi network:
- Signal-mediated diversion to lysosomes
- Signal-mediated diversion to secretory vesicles (for regulated secretion)
- Constitutive secretory pathway
Transcytosis in the indirect plasma membrane protein sorting pathway?
A protein is retrieved from the inappropriate plasma membrane domain (apical/basolateral) by endocytosis and then transported to the correct domain via EARLY ENDOSOMES.
