Trafficking Flashcards
Vesicle definition
spherical particle enclosed by a membrane, containing macromolecules
Pinocytosis definition
Smaller invaginations of the cell membrane fuse and entrap extracellular fluid and its dissolved contents. Resulting pinocytotic vesicles move inwards and fuse with lysosomes or move across the cell and release contents on the other side.
Transcytosis definition
Form of pinocytosis where the pinocytotic vesicles move across the cell where they fuse with the opposite membrane and release contents by exocytosis.
Transcytosis function
Accomplishes bulk transfer of dissolved substances across the cell.
Another form of endocytosis
Receptor mediated endocytosis
explain receptor mediated endocytosis
Many intrinsic proteins with receptor binding sites for ligands, such as receptors for protein hormones. Once ligand bind to their receptors the proteins aggregate in a special membrane region that then invaginate and pinch off internally.
What happens once vesicle is within the cell?
Fuses with an endosomal compartment
What occurs in the endosomal compartment?
outer proteins are removed and recycled
Exocytosis definition
movement of large molecules from inside to outside the cell, triggered by the transient increase of cytosolic calcium ions.
Two pathways of exocytosis
Constitutive and regulative secretion
Explain constitutive secretion
used for products that are continually released from the cell as soon as synthesis is complete, such as keratin or collagen
Regulative secretion
occurs in response to signals coming to the cells, such as the release of digestive enzymes from pancreatic cells in response to a certain stimuli. Occurs mainly at apical domains of cells, constituting glandular secretion
Membrane trafficking definition
The movement and recycling of the plasma membrane- portions of the cell membrane become part of the endocytotic vesicles , during exocytosis the membrane is returned
